How fast does levothyroxine work?


7 Things Your Pharmacist Wants You to Know About Hypothyroidism Medication


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For many people with hypothyroidism, levothyroxine — the most common form of synthetic thyroid hormone medication — can help restore hormone levels and alleviate symptoms. Continued regular use of the medication is essential, however, even when thyroid hormone levels are restored.

While a doctor may be the one who diagnoses your hypothyroidism and prescribes medication, when it comes to managing your treatment regimen, your pharmacist can be a valuable member of your care team and can offer essential advice about medication maintenance.

In addition, pharmacists can inform you of potential drug interactions, instruct you on when to take your daily dose, offer insight on what to expect from treatment, and advise you on how to manage life changes like weight gain or loss.

These are the top seven things pharmacists want you to know about hypothyroidism medication:

Getting better takes time. The medication used to treat hypothyroidism is long acting, so in the beginning, it may take weeks before you experience improvement. When you start levothyroxine you won’t feel better the next day. You may not feel better in two weeks. But symptoms should start disappearing within a month. After six weeks of treatment, you should be almost completely free of symptoms, assuming you’re at the right medication level. If not, you may have to work with your doctor for a while on adjusting your dosage to get it just right.

Generally, hypothyroidism is the type of condition that won’t change from one day to the next but over weeks. A test for thyroid-stimulating hormone (TSH) that identifies thyroxine (T4) and triiodothyronine (T3) levels in the blood is important for diagnosis and for treatment, but changes in medication can take a long time — about six weeks — to be reflected in test results.

“We can certainly change medication levels, but we have to wait six weeks every time we make a change with a dose or have a new medication interaction,” says Rachael W. Duncan, PharmD, BCPS, an emergency medicine clinical pharmacist at Swedish Medical Center in Englewood, Colorado.

Even if you feel your symptoms are under control, the American Thyroid Association (ATA) says you should have your TSH levels tested periodically so your medication can be adjusted if needed.

If you miss a dose, it’s not the end of the world. Even if you miss a dose of your medication, you’re unlikely to have a bad day. Because this type of medication builds up in your system, missing a dose isn’t a huge deal. But remember that the best way to manage hypothyroidism is to take your medication regularly and consistently. You should take your medication at the same time and in the same way every day. If you do miss a dose, the ATA says to take the missed dose as soon as possible, or to take two pills the following day — one in the morning and one in the evening. And never stop taking your medication without talking to your doctor.

Always take your medication on an empty stomach. Food and other medications can bind to levothyroxine and prevent its absorption, meaning that you may not get the full dose of your medication. So avoid eating or taking any other medications within an hour of taking your daily dose of thyroid replacement hormone. You should take your medication with a glass of water, however.

An easy way to ensure you’re taking your medication on an empty stomach is to take it first thing in the morning and to wait an hour before eating. But for those who want to eat within an hour of rising, this approach may not work. Taking your daily pill at bedtime may be an adequate adjustment, so long as you’re not an evening snacker.

Don’t take your medication with multivitamins, antacids, or iron supplements. Just as food can, antacids and iron supplements can bind with your hypothyroidism medication and prevent its absorption. Build a time buffer between taking your thyroid medication and taking any other medications, as well as any antacids, multivitamins, or other supplements, like iron.

Discuss any treatment changes with your pharmacist. While your pharmacist should have access to your medication profile, it doesn’t hurt to discuss medication changes — for hypothyroidism or another condition — with him or her. Some medications are processed by the same enzyme in the liver as levothyroxine — this could interfere enough with your thyroid medication to require dosage adjustments.

You should also discuss any potential changes to the brand of thyroid medication that you take. The ATA says that you should not switch from one brand of thyroid medication to another, from your brand to a generic, or from one generic to another without talking to your doctor first. This is because there may be variation in hormone content among thyroid medications.

Hormones matter, and so could weight changes. Hypothyroidism is five to eight times as likely to occur in women as men, according to the ATA. And some life changes that women experience — like pregnancy — can require a dose change.

What’s more, if you gain weight, you might need a higher dose; similarly, if you lose weight, you might need a lower dose. While your pharmacist can’t prescribe a new dose of medication, a discussion of how certain life changes can affect your treatment can be informative.

Managing hypothyroidism is a lifelong commitment, so it’s important to stick with your medication. “Just because you’re feeling better doesn’t mean you should stop taking your medication,” says Duncan. “You’re feeling better because you’re taking your medication.” If you stop taking your medication, symptoms such as lethargy, coldness, and weight gain are sure to return.

But most of all, remember to be patient!

It can take a while to get your dose dialed in and the entire process can take months.

Don’t let this discourage you, however, because there is a high chance that you will get to where you need to be.

Just remember:

It’s not normal to feel poorly if you are still taking thyroid medication.

#1. You are taking your medication with food.

One simple thing to remember when you take thyroid medication is to never take it with food!

The only thyroid medication that you can take with food is Tirosint (2) (and even then it’s probably not recommended).

Typical thyroid medications such as levothyroxine and Synthroid absorption can be blocked if you take them with food.

This is why your Doctor (and pharmacist) should have told you to take your medication on an empty stomach.

Whether or not you listened to them is a different story!

Taking your medication with food in your stomach may limit the amount of thyroid hormone your body can absorb (3).

So, even if you are taking the right medication, at the right time, in the right dose, it’s still possible that it’s not getting into your body.

Make sure you take your medication on empty stomach and give yourself enough time before you eat.

Most people recommend no food 1-4 hours before or after you take your medication.

You can learn more about other tips and tricks when taking your thyroid medication in this post here.

#2. Your dose isn’t high enough.

Another common reason you may not be feeling better is that your dose is simply not high enough!

This actually happens a fair amount.


Because your doctor would much rather accidentally underdose you than overdose you.

Doctors do the same thing with other medications such as insulin for diabetics (4).

But, even if your doctor wants to get you on the right dose, the chances of him or her putting you on the exact amount that your body needs on the first try is very slim.

In the vast majority of thyroid patients, it takes at least 2-5 dose adjustments before you find what works well for your body.

And, because you shouldn’t check your thyroid labs sooner than 6 weeks, it can take several months for you to fine-tune your dose.

The good news is that you don’t have to get your dose to the perfect range for you to start feeling better, however.

Along the way, as you adjust your dose, you should notice small but incremental changes to your symptoms (in a positive way).

Don’t be afraid to ask your doctor to check your thyroid lab tests if you aren’t feeling back to 100%.

#3. You need a different type of thyroid medication.

Most patients with hypothyroidism are started on medication such as Levothyroxine or Synthroid.

But there are actually many more different types of thyroid medications available than just these.

Some medications get a bad reputation for unfair reasons, but that’s just the way it is.

The reality is that these medications have their place in the treatment of certain patients and it’s possible that you are one of them.

You can split thyroid medications into 3 main groups:

  • T4 only thyroid medications
  • T4 + T3 thyroid medications
  • T3 only thyroid medications

If you aren’t feeling well on T4 only thyroid medication (which is what Synthroid and levothyroxine are) then you may want to at least trial the other medications in the list above.

These medications can sometimes be trickier to dose, but it’s absolutely worth it if it means that you feel better.

#4. You are taking your medication with coffee.

You may be taking your medication without food but are you taking it with your morning coffee?

Coffee is another factor which may be influencing your thyroid hormone absorption and one that you aren’t even considering!

Coffee has the effect of increasing the kinetic movement of your bowels.

Basically, coffee speeds up the movement of your bowels because of the caffeine content in it which is one of the reasons it can cause you to have a bowel movement.

This may be a desirable effect for you, but it doesn’t do any good for thyroid hormone absorption.

The faster your bowels move the shorter amount of time your medication has to be absorbed in the intestinal tract.

If you are taking your medication with coffee in the morning, you may want to think twice!

If you absolutely have to have your morning coffee then you may find more success switching to Tirosint which is still absorbed even while eating or drinking coffee (5).

#5. You aren’t waiting long enough.

This may not be what you want to hear but it may be the truth.

Sometimes it’s just a matter of time before your thyroid medication kicks in.

The average length of time it takes for most people to notice a difference is around 6 weeks.

But that is just the average.

Some people notice a difference almost immediately (after the first pill) while it may take others longer than the 6 week period of noticeable improvement.

How quickly (or slowly) it takes to work in your body will depend on how deficient you are, what other problems you are dealing with, and how much thyroid medication you are absorbing.

If you haven’t noticed significant improvement after 6-8 weeks then don’t be afraid to go back to your doctor to get your labs re-tested and medication adjusted if necessary.

#6. Your thyroid isn’t your main problem.

Another potential explanation has to do with factors unrelated to your thyroid.

It’s actually possible (and common) for hypothyroid patients to also suffer from OTHER medical conditions.

And these problems can cause symptoms which mimic hypothyroidism.


Some of the most common symptoms of hypothyroidism include hair loss, fatigue, and weight gain.

There are so many other conditions that can cause these exact same symptoms.

Conditions such as nutrient deficiencies, insulin resistance, leptin resistance, adrenal fatigue, and so on.

If you’re taking thyroid medication and your lab tests look good but you still remain symptomatic, then you may need to take a look at these other factors.

#7. You aren’t being consistent.

If you want your thyroid medication to work then you need to be consistent while taking it.

What do I mean?

I mean taking it at the same time each and every day.

By maintaining consistency in how you take your medication you will help even out absorption and bloodstream levels of the hormone.

If you are taking your medication at 6:00am one morning then 8:00am the next morning or skipping a day here or there then that may explain your persistent symptoms.

Pick a time to take your medication and stick to it.

#8. Other medications are interfering with your medication.

Lastly, another factor worth considering has to do with other medications that you might be taking.

It’s not uncommon for other medications to interfere with thyroid medication.

Not all medications do this, but there are certain medications which tend to cause problems.

Medications which interfere with thyroid hormone include:

If you are on any of these medications you may want to touch base with your Doctor to see if you can find another option.

Whatever you do, don’t stop taking your medication cold turkey without discussing it with your Doctor!

In many cases, you may be able to switch to a different type or class of medication which can often help.

How Long After Starting Medication Will it Take to Lose Weight?

When should you expect to magically lose all of the weight you’ve gained from hypothyroidism?

Unfortunately, the answer is that most people do NOT lose weight after starting thyroid medication (especially T4 only thyroid medications).

If you are one of the lucky few people who will lose weight after starting your medication then it will most likely occur slowly and over a period of 3 to 6 months.

You will probably notice a small amount of weight loss on the scale but over time you should notice that your clothes fit better.

It’s important to note that this is not common.

Don’t let this get you down, however, because there are still definitely ways for you to lose weight if you have thyroid disease.

Why don’t most people lose weight?

It has to do with what medication you are using, your dose, your free thyroid hormone levels, and other hormones in your body.

Simply taking thyroid medication isn’t enough to solve all of these problems but it is a good step in the right direction.

When it comes to weight loss, most hypothyroid patients find success using medications which contain T3 (medications such as Armour thyroid and Cytomel).

This has to do with the fact that your free T3 levels (and total T3) tend to correlate with weight loss (10).

The higher your T3 levels the more weight you will lose.

Standard thyroid medications like levothyroxine do not contain T3 thyroid hormone and so people on these medications may still experience low T3 even though they are taking it.


If you are taking thyroid medication then you should allow a good 6 weeks from your start date before you start getting worried about whether it is working for you or not.

Thyroid medication tends to take time to work as it alters genetic transcription inside of your cells.

This waiting game can be frustrating, but it’s just how it goes.

There are also many other reasons which can limit how effective your thyroid medication can be.

If you have been taking your thyroid medication faithfully for 6 weeks or longer then you may want to look at these other factors.

Now I want to hear from you:

Are you taking thyroid medication right now?

Are you feeling better?

How long did it take for you to notice a difference? Are you still waiting?

Leave your questions or comments below!

Ask a Thyroid Expert

For More Information

On Cleveland Clinic

Cleveland Clinic is a national leader in caring for patients with all types of thyroid conditions, from the routine to the complex. Our patients benefit from access to a multidisciplinary staff, the most advanced technology and the latest clinical trials for thyroid conditions.

Cleveland Clinic’s Thyroid Center has nationally and internationally recognized expertise in thyroid ultrasound, novel diagnostic markers and genetic evaluations of thyroid cancer patients. It is one of only a few centers nationwide to provide radiofrequency ablation of liver metastases from thyroid cancer and have robotic surgery expertise.

Our high-volume center is the home of the largest thyroid cancer surgical program in Ohio and the five surrounding states, performing more than 500 endocrine surgical procedures every year―many of which are complex and reoperative surgeries.

The center is structured for collaboration among experts from a variety of Cleveland Clinic specialties, including endocrinologists, endocrine surgeons, pathologists, radiologists, genomic medicine experts and oncologists from Taussig Cancer Institute, as well as the physicians and surgeons from other Cleveland Clinic Institutes, when needed.

The Endocrinology & Metabolism Institute at Cleveland Clinic includes the departments of endocrine surgery; endocrinology, diabetes and metabolism along with the thyroid center, diabetes center, and endocrine calcium clinic. We treat various disease and conditions of the endocrine system, including diabetes (types 1 and 2), obesity, hyper- and hypothyroidism, Cushing disease, and Addison disease among other illnesses.

The Endocrinology & Metabolism Institute at Cleveland Clinic is ranked first in Ohio and second in the United States by U.S.News and World Report.

For Thyroid Health Information

The following health articles may provide additional information:

  • Thyroid Disease
  • Thyroid Cancer
  • Hypothyroidism
  • Hyperthyroidism
  • Post Partum Thyroiditis
  • Thyroidectomy
  • Goiter
  • Hashimoto’s Disease
On Your Health

MyChart®: Your Personal Health Connection, is a secure, online health management tool that connects Cleveland Clinic patients with their personalized health information. All you need is access to a computer. For more information about MyChart®, call toll-free at 866.915.3383 or send an email to: [email protected]

A remote second opinion may also be requested from Cleveland Clinic through the secure Cleveland Clinic MyConsult® website. To request a remote second opinion, visit

This information is provided by Cleveland Clinic as a convenience service only and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. Please remember that this information, in the absence of a visit with a health care professional, must be considered as an educational service only and is not designed to replace a physician’s independent judgment about the appropriateness or risks of a procedure for a given patient. The views and opinions expressed by an individual in this forum are not necessarily the views of the Cleveland Clinic institution or other Cleveland Clinic physicians. ©Copyright 1995-2014. The Cleveland Clinic Foundation. All rights reserved.

Reviewed: 02/14

How long does 50mcg take to leave your System ? Side affects from medicine

Hello Hlxxxx, it took months for the levo to fully get out of my system, but I was on 200mcg for nearly three years. I felt as if the bulk of it was out after three months. This was the worst if it, as I could smell the chemical detox as it came out. After 6 months, much better, now it’s a year and I’m still improving. I can totally understand the horrible side effects. I had extremely bad side effects and the medication didn’t work for me at any dose. Synthroid was the worst as far as side effects, as it contains additives that trigger the immune system. I tried compounded for several years, But it never really worked and my thyroid disease worsened dramatically, as shown by a massive increase in thyroid cysts. With the compounded, the side effects were less, but really, it didn’t work at any dose. My feeling is that if it doesn’t work initially, it won’t improve enough to be effective.

You might try NDT, Armour, if your thyroid disease is mild. Also, OTC ThyroGold is excellent, and is the closest biologically to human thyroxins. American Biologics makes a fairly good product as well. Just some things to try.

None of the thyroid meds are truly bio identical, so you’ll have a tough time with the thyroid meds no matter what.

Also, since you’re on a low dose, you may be able to reverse the thyroid disease with diet and nutrition. Time consuming but worthwhile.

Do read through the many posts here, especially, “unacceptable side effects of levothyroxin”, as you’ll find that others have had similar experiences, and are supportive and offer many excellent bits of advice.

Hope that’s helpful.





Levothyroxine has a narrow therapeutic index. Regardless of the indication for use, careful dosage titration is necessary to avoid the consequences of over- or under-treatment. These consequences include, among others, effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, emotional state, gastrointestinal function, and on glucose and lipid metabolism. Many drugs interact with levothyroxine sodium necessitating adjustments in dosing to maintain therapeutic response (see DRUG INTERACTIONS).

Effects On Bone Mineral Density

In women, long-term levothyroxine sodium therapy has been associated with decreased bone mineral density, especially in postmenopausal women on greater than replacement doses or in women who are receiving suppressive doses of levothyroxine sodium. Therefore, it is recommended that patients receiving levothyroxine sodium be given the minimum dose necessary to achieve the desired clinical and biochemical response.

Patients With Underlying Cardiovascular Disease

Exercise caution when administering levothyroxine to patients with cardiovascular disorders and to the elderly in whom there is an increased risk of occult cardiac disease. In these patients, levothyroxine therapy should be initiated at lower doses than those recommended in younger individuals or in patients without cardiac disease (see WARNINGS; PRECAUTIONS, Geriatric Use; and DOSAGE AND ADMINISTRATION ). If cardiac symptoms develop or worsen, the levothyroxine dose should be reduced or withheld for one week and then cautiously restarted at a lower dose. Overtreatment with levothyroxine sodium may have adverse cardiovascular effects such as an increase in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias. Patients with coronary artery disease who are receiving levothyroxine therapy should be monitored closely during surgical procedures, since the possibility of precipitating cardiac arrhythmias may be greater in those treated with levothyroxine. Concomitant administration of levothyroxine and sympathomimetic agents to patients with coronary artery disease may precipitate coronary insufficiency.

Patients With Nontoxic Diffuse Goiter Or Nodular Thyroid Disease

Exercise caution when administering levothyroxine to patients with nontoxic diffuse goiter or nodular thyroid disease in order to prevent precipitation of thyrotoxicosis (see WARNINGS ). If the serum TSH is already suppressed, levothyroxine sodium should not be administered (see CONTRAINDICATIONS).

Associated Endocrine disorders

Hypothalamic/Pituitary Hormone Deficiencies

In patients with secondary or tertiary hypothyroidism, additional hypothalamic/pituitary hormone deficiencies should be considered, and, if diagnosed, treated (see PRECAUTIONS, Autoimmune polyglandular syndrome) for adrenal insufficiency.

Autoimmune Polyglandular Syndrome

Occasionally, chronic autoimmune thyroiditis may occur in association with other autoimmune disorders such as adrenal insufficiency, pernicious anemia, and insulin-dependent diabetes mellitus. Patients with concomitant adrenal insufficiency should be treated with replacement glucocorticoids prior to initiation of treatment with levothyroxine sodium. Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated, due to increased metabolic clearance of glucocorticoids by thyroid hormone. Patients with diabetes mellitus may require upward adjustments of their antidiabetic therapeutic regimens when treated with levothyroxine (see PRECAUTIONS, DRUG INTERACTIONS).

Other Associated Medical Conditions

Infants with congenital hypothyroidism appear to be at increased risk for other congenital anomalies, with cardiovascular anomalies (pulmonary stenosis, atrial septal defect, and ventricular septal defect,) being the most common association.

Laboratory Tests

The diagnosis of hypothyroidism is confirmed by measuring TSH levels using a sensitive assay (second generation assay sensitivity ≤0.1 mIU/L or third generation assay sensitivity ≤0.01 mIU/L) and measurement of free-T4.

The adequacy of therapy is determined by periodic assessment of appropriate laboratory tests and clinical evaluation. The choice of laboratory tests depends on various factors including the etiology of the underlying thyroid disease, the presence of concomitant medical conditions, including pregnancy, and the use of concomitant medications (see PRECAUTIONS, DRUG INTERACTIONS and Drug- Laboratory Test Interactions). Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose of LEVOXYL may be evidence of inadequate absorption, poor compliance, drug interactions, or decreased T4 potency of the drug product.


In adult patients with primary (thyroidal) hypothyroidism, serum TSH levels (using a sensitive assay) alone may be used to monitor therapy. The frequency of TSH monitoring during levothyroxine dose titration depends on the clinical situation but it is generally recommended at 6 – 8 week intervals until normalization. For patients who have recently initiated levothyroxine therapy and whose serum TSH has normalized or in patients who have had their dosage or brand of levothyroxine changed, the serum TSH concentration should be measured after 8 – 12 weeks. When the optimum replacement dose has been attained, clinical (physical examination) and biochemical monitoring may be performed every 6 – 12 months, depending on the clinical situation, and whenever there is a change in the patient’s status. It is recommended that a physical examination and a serum TSH measurement be performed at least annually in patients receiving LEVOXYL (see WARNINGS , PRECAUTIONS, and DOSAGE AND ADMINISTRATION ).


In patients with congenital hypothyroidism, the adequacy of replacement therapy should be assessed by measuring both serum TSH (using a sensitive assay) and total- or free- T4. During the first three years of life, the serum total- or free- T4 should be maintained at all times in the upper half of the normal range. While the aim of therapy is to also normalize the serum TSH level, this is not always possible in a small percentage of patients, particularly in the first few months of therapy. TSH may not normalize due to a resetting of the pituitary-thyroid feedback threshold as a result of in utero hypothyroidism. Failure of the serum T to increase into the upper half of the normal range within 2 weeks of initiation of LEVOXYL therapy and/or of the serum TSH to decrease below 20 mU/L within 4 weeks should alert the physician to the possibility that the child is not receiving adequate therapy. Careful inquiry should then be made regarding compliance, dose of medication administered, and method of administration prior to raising the dose of LEVOXYL.

The recommended frequency of monitoring of TSH and total or free T4 in children is as follows: at 2 and 4 weeks after the initiation of treatment; every 1 – 2 months during the first year of life; every 2 – 3 months between 1 and 3 years of age; and every 3 to 12 months thereafter until growth is completed. More frequent intervals of monitoring may be necessary if poor compliance is suspected or abnormal values are obtained. It is recommended that TSH and T4 levels, and a physical examination, if indicated, be performed 2 weeks after any change in LEVOXYL dosage. Routine clinical examination, including assessment of mental and physical growth and development, and bone maturation, should be performed at regular intervals (see PRECAUTIONS, Pediatric Use and DOSAGE AND ADMINISTRATION).

Secondary (Pituitary) And Tertiary (Hypothalamic) Hypothyroidism

Adequacy of therapy should be assessed by measuring serum free-T4 levels ,which should be maintained in the upper half of the normal range in these patients.

Drug-Food Interactions

Consumption of certain foods may affect levothyroxine absorption thereby necessitating adjustments in dosing. Soybean flour (infant formula), cotton seed meal, walnuts, and dietary fiber may bind and decrease the absorption of levothyroxine sodium from the GI tract.

Drug-Laboratory Test Interactions

Changes in TBG concentration must be considered when interpreting T4 and T3 values, which necessitates measurement and evaluation of unbound (free) hormone and/or determination of the free T4 index (FT4I). Pregnancy, infectious hepatitis, estrogens, estrogen-containing oral contraceptives, and acute intermittent porphyria increase TBG concentrations. Decreases in TBG concentrations are observed in nephrosis, severe hypoproteinemia, severe liver disease, acromegaly, and after androgen or corticosteroid therapy (see also Table 2). Familial hyper- or hypo-thyroxine binding globulinemias have been described, with the incidence of TBG deficiency approximating 1 in 9000.

Carcinogenesis, Mutagenesis, And Impairment Of Fertility

Animal studies have not been performed to evaluate the carcinogenic potential, mutagenic potential or effects on fertility of levothyroxine. The synthetic T4 in LEVOXYL is identical to that produced naturally by the human thyroid gland. Although there has been a reported association between prolonged thyroid hormone therapy and breast cancer, this has not been confirmed. Patients receiving LEVOXYL for appropriate clinical indications should be titrated to the lowest effective replacement dose.


Category A

Studies in women taking levothyroxine sodium during pregnancy have not shown an increased risk of congenital abnormalities. Therefore, the possibility of fetal harm appears remote. LEVOXYL should not be discontinued during pregnancy and hypothyroidism diagnosed during pregnancy should be promptly treated.

Hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, pre-eclampsia, stillbirth and premature delivery. Maternal hypothyroidism may have an adverse effect on fetal and childhood growth and development. During pregnancy, serum T4 levels may decrease and serum TSH levels increase to values outside the normal range. Since elevations in serum TSH may occur as early as 4 weeks gestation, pregnant women taking LEVOXYL should have their TSH measured during each trimester. An elevated serum TSH level should be corrected by an increase in the dose of LEVOXYL. Since postpartum TSH levels are similar to preconception values, the LEVOXYL dosage should return to the pre-pregnancy dose immediately after delivery. A serum TSH level should be obtained 6 – 8 weeks postpartum.

Thyroid hormones do not readily cross the placental barrier; however, some transfer does occur as evidenced by levels in cord blood of athyreotic fetuses being approximately one-third maternal levels. Transfer of thyroid hormone from the mother to the fetus, however, may not be adequate to prevent in utero hypothyroidism.

Nursing Mothers

Although thyroid hormones are excreted only minimally in human milk, caution should be exercised when LEVOXYL is administered to a nursing woman. However, adequate replacement doses of levothyroxine are generally needed to maintain normal lactation.

Pediatric Use

The goal of treatment in pediatric patients with hypothyroidism is to achieve and maintain normal intellectual and physical growth and development.

The initial dose of levothyroxine varies with age and body weight (see DOSAGE AND ADMINISTRATION, Table 3). Dosing adjustments are based on an assessment of the individual patient’s clinical and laboratory parameters (see PRECAUTIONS, Laboratory Tests). In children in whom a diagnosis of permanent hypothyroidism has not been established, it is recommended that levothyroxine administration be discontinued for a 30-day trial period, but only after the child is at least 3 years of age. Serum T4 and TSH levels should then be obtained. If the T4 is low and the TSH high, the diagnosis of permanent hypothyroidism is established, and levothyroxine therapy should be reinstituted. If the T4 and TSH levels are normal, euthyroidism may be assumed and, therefore, the hypothyroidism can be considered to have been transient. In this instance, however, the physician should carefully monitor the child and repeat the thyroid function tests if any signs or symptoms of hypothyroidism develop. In this setting, the clinician should have a high index of suspicion of relapse. If the results of the levothyroxine withdrawal test are inconclusive, careful follow-up and subsequent testing will be necessary.

Since some more severely affected children may become clinically hypothyroid when treatment is discontinued for 30 days, an alternate approach is to reduce the replacement dose of levothyroxine by half during the 30-day trial period. If, after 30 days, the serum TSH is elevated above 20 mU/L, the diagnosis of permanent hypothyroidism is confirmed, and full replacement therapy should be resumed. However, if the serum TSH has not risen to greater than 20mU/L, levothyroxine treatment should be discontinued for another 30-day trial period followed by repeat serum T4 and TSH.

The presence of concomitant medical conditions should be considered in certain clinical circumstances and, if present, appropriately treated (see PRECAUTIONS).

Congenital Hypothyroidism


Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on intellectual development as well as on overall physical growth and maturation. Therefore, LEVOXYL therapy should be initiated immediately upon diagnosis and is generally continued for life.

During the first 2 weeks of LEVOXYL therapy, infants should be closely monitored for cardiac overload, arrhythmias, and aspiration from avid suckling.

The patient should be monitored closely to avoid undertreatment or overtreatment. Undertreatment may have deleterious effects on intellectual development and linear growth. Overtreatment has been associated with craniosynostosis in infants, and may adversely affect the tempo of brain maturation and accelerate the bone age with resultant premature closure of the epiphyses and compromised adult stature.

Acquired Hypothyroidism In Pediatric Patients

The patient should be monitored closely to avoid undertreatment and overtreatment. Undertreatment may result in poor school performance due to impaired concentration and slowed mentation and in reduced adult height. Overtreatment may accelerate the bone age and result in premature epiphyseal closure and compromised adult stature.

Treated children may manifest a period of catch-up growth, which may be adequate in some cases to normalize adult height. In children with severe or prolonged hypothyroidism, catch-up growth may not be adequate to normalize adult height.

Geriatric Use

Because of the increased prevalence of cardiovascular disease among the elderly, levothyroxine therapy should not be initiated at the full replacement dose (see WARNINGS , PRECAUTIONS, and DOSAGE AND ADMINISTRATION).

Hypothyroidism is caused by a variety of factors, and adults, particularity women, should have a blood test to determine thyroid problems every 5 years to detect the condition and treat it effectively.
Hypothyroidism is an endocrine condition characterized by having an underactive thyroid gland, which results in a deficiency in the thyroid hormone. The thyroid gland is a butterflyshaped gland located in the front of the neck just below the voice box (larynx) and it releases the hormones that regulate the body’s energy and control metabolism. When levels of thyroid hormone are low, the body burns energy slower than normal and the heart rate and regulation of body temperature decrease as well.
Statistics show that an estimated 1% of all adults in the United States have some degree of hypothyroidism and that this condition affects an estimated 10% of patients in the elderly population.1 According to the American Association of Clinical Endocrinologists, an estimated 25 million people have some form of hypothyroidism, but only half have been diagnosed.2 While hypothyroidism can affect anyone at any age, it is most prevalent among females and affects an estimated 10% of women and 6% of men.

The disease is also more common among individuals older than 60 years. The American Thyroid Association recommends that adults, particularly women, have a blood test to detect thyroid problems every 5 years starting at age 35.3
While rare, hypothyroidism can also be caused by too much or too little intake of dietary iodine or by abnormalities of the pituitary gland. Certain factors may increase your chance of developing thyroid disorders. You may require more regular testing if you have2,3:
• A previous thyroid problem, such as goiter or thyroid surgery
• A family history of thyroid disease
• Other autoimmune diseases including Sjögren’s syndrome, pernicious anemia, type 1 diabetes, rheumatoid arthritis, or lupus
• Turner syndrome, a genetic disorder that affects girls and women who are older than 60 years
• Been pregnant or delivered a baby within the past 6 months
• Received radiation to the thyroid or to the neck or chest.
Signs and Symptoms Asociated with Hypothyroidism
Hypothyroidism rarely causes symptoms in the early stages, but if left untreated over time it can cause a number of medical problems such as infertility, obesity, heart problems, and joint pain.
The symptoms associated with hypothyroidism can vary from patient to patient. The most common symptoms associated with hypothyroidism include:
• Fatigue, lack of energy
• Unintentional weight gain
• Puffy face
• Cold intolerance
• Joint stiffness and muscle pain
• Constipation
• dry skin
• dry, brittle, and thinning hair or fingernails
• hair loss
• Decreased sweating
• heavy or irregular menstrual periods
• Infertility issues
• depression
• decreased heart rate
• elevated cholesterol levels
If left untreated, patients may experience1,4:
• decreased taste and smell
• hoarseness
• puffy face, hands, and feet
• slow speech
• thickening of the skin
• thinning of eyebrows
Myxedema coma is referred to as the most severe form of hypothyroidism, and rarely occurs.1,3,4 It may be caused by an infection, illness, exposure to cold, or certain medications in individuals with untreated hypothyroidism. The symptoms and signs associated with myxedema coma include below normal temperature, shallow breathing, low blood pressure, and blood glucose, as well as unresponsiveness. 1,3,4
Diagnosis of Hypothyroidism
If your doctor suspects that you have hypothyroidism, he or she will obtain a blood sample and test your levels of thyroid hormone.
If you have been diagnosed with hypothyroidism your doctor will prescribe a synthetic form of the thyroid hormone. Levothyroxine, a synthetic thyroid hormone product, is the standard treatment for managing hypothyroidism and is available under various brand names (eg, Levothroid, Synthroid). The good news is that hypothyroidism can almost always be completely controlled with the use of synthetic levothyroxine, as long as the recommended dose is taken daily as instructed.
The exact dose will depend on your age and weight, the severity of the hypothyroidism, the presence of other health problems, and whether you are taking other drugs that might interfere with how well the body uses the thyroid hormone.
About 1 to 2 weeks after you start treatment with levothyroxine, you will likely notice that your levels of fatigue have improved. It is important that you take your medication exactly as prescribed and not miss any doses as well as maintain routine checkups with your primary health care provider.
Your doctor will monitor your thyroid stimulating hormone (TSH) levels about 6 to 8 weeks after you begin therapy and make any necessary dosage adjustments when warranted. If your dose needs to be adjusted, you will require more labs to check your TSH levels. Once you are at a stable dose, your doctor will typically require you to have blood tests repeated in 6 months, and then once a year after that.
While hypothyroidism cannot be prevented, you can lead a normal and productive life if you take your medicine as prescribed. Some important things to remember once you start taking thyroid hormone medication include3,4:
• Take your medication exactly as directed by your doctor daily and at the same time every day.
• Since absorption of this medication is increased on an empty stomach, take your thyroid medicine on an empty stomach 30 minutes to an hour before breakfast.
• Do not stop taking the medication even if you feel better.
• Do not take your thyroid medication at the same time as fiber supplements, calcium, iron, multivitamins, or aluminum hydroxide antacids or any medications that bind bile acids. Take your thyroid medication and these medications at least 4 hours apart.
• After you start taking replacement therapy, if you have any adverse effects or concerns, you should immediately report them to your primary health care provider. Excessive amounts of thyroid hormone can cause various adverse effects which include palpitations, rapid weight loss, restlessness or shakiness, sweating, and insomnia.4 PT
This handout for patients is available online at

1. Hypothyroidism. Patient Education Center Web site. Accessed November 10, 2010.
2. What is Hypothyroidism? Abbott Laboratories Web site. Accessed November 10, 2010.
3. Hypothyroidism. Medline Plus Web site. Accessed November 10, 2010.
4. Hypothyroidism. Mayo Clinic Web site. Accessed November 10, 2010.
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.

Modern management of thyroid replacement therapy

If taken correctly, thyroxine should enable patients to lead a normal life. However, there are some common problems which can affect management.

Persistently elevated TSH

Poor adherence is the most likely explanation of TSH remaining above the normal range. I advise patients to decant a week’s supply of thyroxine into a separately labelled bottle and refill the bottle on the same day each week. If the patient discovers they have missed one (or more) doses they can take the missed doses in conjunction with their usual dose over the next few days.

The absorption of thyroxine may be reduced by cholestyramine, colestipol, aluminium hydroxide, ferrous sulfate and possibly fibre. Two hours should elapse between use of thyroxine and these drugs.

Symptoms do not respond to thyroxine

Hypothyroidism is often discovered on biochemical testing after patients present with non-specific complaints. While it is likely that symptoms such as muscle aches and pains, dry skin and dry hair and menstrual irregularity may respond to thyroxine, other symptoms such as lethargy, tiredness and fatigue, weight gain and depressive symptoms may have other causes. It is helpful to consider if the patient’s symptoms are likely to be due to hypothyroidism before prescribing thyroxine and to tell them if you suspect that some of their symptoms are unlikely to respond. There is no proven benefit in adding liothyronine to the treatment of patients who have persistent symptoms despite taking thyroxine.

Secondary hypothyroidism

If there is pituitary or hypothalamic disease, TSH is unreliable for diagnosing and monitoring thyroid function and fT4 should be used instead. A low fT4 will be found in secondary hypothyroidism and treatment should aim to maintain fT4 within the reference range.

Most patients with secondary hypothyroidism will be hypogonadal and many will also be cortisol deficient. It is extremely important to consider cortisol deficiency before starting treatment with thyroxine in patients with pituitary and hypothalamic disease as its use will speed the metabolism of cortisol and can induce an adrenal crisis.

When commencing thyroxine in secondary hypothyroidism it is therefore safest to also treat the patient with a corticosteroid (for example prednisone 5 mg daily). Subsequently, cortisol reserve can be assessed with an early morning cortisol measurement. A morning cortisol less than 100 nmol/L always indicates the need for ongoing steroid replacement. Results greater than 500 nmol/L indicate adequate reserve and values in between may require provocation tests.5

Drug-induced hypothyroidism

Lithium and iodine are the common causes of drug-induced hypothyroidism. Amiodarone, iodine-containing contrast media and kelp tablets are common sources of large doses of iodine.

All forms of drug-induced hypothyroidism will usually resolve on withdrawal of the drug. Thyroxine can be used to control symptoms if required while recovery occurs. Lithium- and amiodarone-induced hypothyroidism are managed with thyroxine. The ongoing need for the lithium or amiodarone should be considered, but they can be continued if necessary.

Pregnancy and lactation

Thyroxine requirements increase by 25-30% during pregnancy with increased requirements seen as early as the fifth week of pregnancy.6Children born to women whose hypothyroidism was inadequately treated in pregnancy are at increased risk of neuropsychological impairment.7

I advise women taking thyroxine who are planning to conceive to increase their dose of thyroxine by 30% at the confirmation of the pregnancy. TSH should be monitored every 8-10 weeks during pregnancy with further dose adjustments as necessary. The thyroxine dose returns to the pre-pregnancy dose after delivery whether the mother is breastfeeding or not.

Transient hypothyroidism

Some patients have transient hypothyroidism so it is appropriate to consider withdrawing the drug. For example, women who develop hypothyroidism in the postpartum period (postpartum thyroiditis) may not require long-term thyroxine replacement. In some patients a clear cause of hypothyroidism is not established, but the cause will often have been the hypothyroid phase of subacute (de Quervain’s) thyroiditis or possibly iodine-induced hypothyroidism. Other patients may ask if they can stop thyroxine therapy.

If treatment is stopped it usually takes four weeks for the TSH to rise, but it can be tested earlier if symptoms occur. The onset of symptoms and a rising TSH show an ongoing need for thyroxine and patients can immediately recommence their previous dose.

Medication for hypothyroidism (underactive thyroid) aims to balance the amount of thyroid stimulating hormone (THS) inside your body and as a result, restore your body’s hormones and metabolism to normal levels.

When starting thyroid medication, it’s important to remember that hypothyroidism, has no one-size-fits-all treatment plan. Determining the best medication for a patient and the right dose requires patients to work with their doctors through a process of trial and error, which can sometimes take several weeks or months to get exactly right.

After a patient’s initial hypothyroidism diagnosis, his or her doctor will likely prescribe a low dose of synthetic thyroid hormone (thyroid medication). The doctor will also schedule follow-up blood tests every six to eight weeks after the patient begins medication. During this time, doctors work with patients, adjusting medication dosages, until a healthy level of thyroid stimulating hormone consistently shows up in blood tests.

Once an appropriate dose has been determined, your doctor will likely schedule a six-month follow-up blood test and appointment and then ongoing annual wellness exams to ensure proper treatment.

Potential Side Effects of Starting Thyroid Medication

When starting thyroid medication for an underactive thyroid, it can take some time working with your doctor to determine the exact dose needed to balance your body’s hormone production. Patients who begin with too high of a dose can experience side effects of the medication which feel similar to the symptoms of hyperthyroidism (overactive thyroid). These side effects include:

  • Heat sensitivity
  • Sweating
  • Anxiety and/or nervousness
  • Shaking
  • Rapid heartbeat
  • Increased appetite
  • Weight loss
  • Brittle hair
  • Thin skin
  • Fatigue
  • Insomnia

If you experience any of these symptoms after starting a new thyroid medication, changing medication brands or after changing the dose of your thyroid medication, you should speak with your doctor.

Reaching Prescription Perfection Takes Patience

Thyroid medications are categorized as having what is called a narrow therapeutic index, which means that even the slightest differences in dosages can make huge differences inside the body. As a result, your doctor might need to make lots of minor adjustments to your prescription before you feel completely normal and healthy again.

For consistent and effective results, medications with a narrow therapeutic index must be taken exactly as prescribed by your doctor, at the same time each day. You can read an article on how to best take thyroid medication. Also, to ensure proper absorption, these medications should also always be taken on an empty stomach and at least four hours apart from other medications, vitamins, and fiber supplements.

Hypothyroidism is, unfortunately, a lifelong condition and usually requires lifelong treatment. After finding the right dose of thyroid medication, certain life changes can affect your body’s chemistry, prompting another period of dose adjustment with your doctor. Physical changes which might lead to an increased or reduced dose include pregnancy, menopause, and the natural aging process.

Since everybody is different, every person will respond a little differently to thyroid medication. When starting a new thyroid medication or adjusting your medication dose, you should stay in close contact with your doctor to discuss any physical changes or side effects you experience.

Here are our 5 top tips on how to deal with Hypothyroidism. With a little patience and a daily reminder, individuals with hypothyroidism should be able to find the right dosage and return to living and enjoying life with restored energy and balance.

A publication of the American Thyroid Association

Summaries for Patients from Clinical Thyroidology (from recent articles in Clinical Thyroidology)
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Taking levothyroxine with breakfast may be fine for many patients

Levothyroxine is the most common therapy for the treatment of hypothyroidism as it is the same as the major thyroid hormone produced by the thyroid gland. The absorption of levothyroxine in the gut is decreased when taking the hormone at the same time as calcium, iron and some foods and other drugs. Because of this, patients are usually instructed to take levothyroxine on an empty stomach 30-60 minutes before food intake to avoid erratic absorption of the hormone. For many patients, this means first thing in the morning before breakfast. This is often difficult for many patients, especially those on multiple medications. This study was performed to see if patients can take their levothyroxine with food in the morning and not have to wait 30-60 minutes.

Perez CL et al. Serum thyrotropin levels following levothyroxine administration at breakfast. Thyroid 2013;23:779-84. Epub June 21, 2013.

This study was performed in Brazil and included 45 patients who had a diagnosis of hypothyroidism and a normal TSH level on levothyroxine therapy. For 90 days patients were assigned either to take the levothyroxine 30-60 minutes be- fore a meal or during the morning meal. Then after 90 days, they switched to the other regimen. TSH levels were assessed at baseline, 45, 90, 135 and 180 days after the start of the study. Patients reported all of their food intake at breakfast. As expected, 90% of the patient population was women.

The average TSH at the start of the study was 1.7. The TSH level was higher when levothyroxine was taken during breakfast (TSH 2.9) as compared with group who waited 30-60 minutes before taking levothyroxine (TSH 1.9). Patient preference was assessed at the end of the study and 41% preferred taking levothyroxine and waiting, 33% preferred taking the levothyroxine with breakfast and 26% indicated no preference.

This study shows that the absorption of levothyroxine is indeed decreased when taking the hormone with breakfast. Despite an increase in TSH while taking the hormone with breakfast, the TSH remained within the normal range. Thus, while taking levothyroxine with breakfast could be an alternative regimen for patients who have difficulties taking the hormone on an empty stomach, this regimen is more likely to cause variability in the TSH level. It is still advised that patients with a history of thyroid cancer, those who are pregnant or those who are very sensitive to changes in their TSH level need to likely wait 30–60 minutes prior to taking there levothyroxine.

—Heather Hofflich, DO



Thyroid Hormone Treatment:

Table of Contents | PDF File for Saving and Printing

A publication of the American Thyroid Association

Summaries for Patients from Clinical Thyroidology (April 2011)
Table of Contents | PDF File for Saving and Printing

When is the best time to take thyroid hormone?

Hypothyroidism is treated by replacement of thyroid hormone in pill form, specifically levothyroxine. It is well documented that food and a number of medications can decrease the absorption of levothyroxine. This is especially true with calcium and iron pills. Consequently, many patients are instructed to take their levothyroxine on an empty stomach before breakfast and to wait up until an hour before eating. Some patients find this timing inconvenient. A prior study suggested that taking levothyroxine at bedtime was equally as effective in providing stable thyroid hormone levels. The goal of this study was to compare the effect of taking levothyroxine at bedtime as opposed to taking it before breakfast.

Bolk N et al. Effects of evening vs. morning levothyroxine intake: A randomized double-blind crossover trial. Arch Intern Med. 2010;170(22):1996-2003.

All patients had hypothyroidism and had been on stable doses of levothyroxine for 6 months when they were assigned to either take levothyroxine on an empty stomach 30 minutes before breakfast or at bedtime. After three months, they switched the timing of levothyroxine to the alternate time (either pre-breakfast or bedtime) for another 3 months, such that all patients experienced both schedules of levothyroxine ingestion. Thyroid hormone, TSH and cholesterol levels were measured every 6 weeks and quality of life questionnaires were assessed every 12 weeks for the 6 month duration of the study. Bedtime levothyroxine ingestion resulted in significantly lower TSH values and higher thyroid hormone levels, indicating improved absorption of levothyroxine when taken at bedtime. There were no significant differences in cholesterol levels or quality of life measures.

This study suggests that taking levothyroxine at bedtime results in better absorption than taking it before breakfast. This confirms that taking levothyroxine at different times can result in different levels of thyroid hormones in the blood, emphasizing the need to take it at the same time every day. However, this also confirms that taking levothyroxine at bedtime is an effective alternative to taking it before breakfast. Further, bedtime may be better in patients who appear to have problems absorbing levothyroxine.

—Whitney Woodmansee, MD



Thyroid Hormone Treatment:

Table of Contents | PDF File for Saving and Printing

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