How long do you have to wait after eating to take levothyroxine?

Gonino Center for Healing Thyroid Medication Instructions It is important that you know how to take your thyroid medication properly. Helpful information including the timing of your medication, interactions with foods, drugs and supplements are covered, as well as creative ways to remember to take your thyroid medication.

  1. Always check the prescription against what you receive.

  2. Dr Gonino feels the ideal time to take thyroid medication is in the morning.

    1. If you sleep well, i.e., sleep 7-9 hours without waking up, Dr Gonino prefers that upon waking you begin your day with prayer.

    2. Set your intent for the day, then eat a healthy breakfast.

    3. Take all of your non-calcium containing supplements with breakfast.

    4. Take Alka Salts and any other Calcium supplements at bedtime.

    5. Take your Thyroid medication 2 hours after breakfast.

      1. Take your thyroid with a full glass of water

      2. Wait one hour before eating after taking your Thyroid medication

**If you tend to wake up early in the morning but before you are ready to start your day, you can have your thyroid on the nightstand, take it then, go back to sleep, or lay in bed, and then you can eat breakfast as early as one hour later.

**In Summary, you can take your thyroid support 2 hours after breakfast, as Dr Gonino does, or an hour before, like Mrs. Gonino does. Dr Gonino doesn’t want you waking up, taking it, and being physically active because that can lower your blood sugar. If you take it first thing, go back to sleep or be fairly still while awake.

Thyroid Inhibiting Foods

  1. Goitrogens: You should limit to one handful per day or less: Kale tops the list, followed by broccoli, cauliflower, cabbage, Brussels sprouts and collard greens.

  2. Be consistent about a high-fiber diet. If you start or stop eating high-fiber, get your thyroid rechecked, because it may change your absorption.

Additional things to know about your Thyroid

  1. Don’t take antacids within two hours of thyroid hormone. Allow at least 2-3 hours apart, so absorption is not affected.

  2. Watch for interactions with antidepressants & thyroid hormone. Zoloft, Paxil and Prozac can make thyroid meds more or less effective. Talk to your doctor.

  3. Missing one day of thyroid can have undesirable effects on hormonal balance resulting in mood, pain and digestive issues.

**Always talk to your doctor about your medications, dosages, and what your doctor recommends for your particular situation.

Hypothyroidism Requires Lifelong Therapy

Thyroid hormone replacement therapy is usually a lifelong treatment. Be sure you always have a fresh supply of medication on hand and always remember to follow your doctor’s directions. Do not stop taking your medication or switch medications unless told to do so by a doctor.

Tell your doctor about any other drugs you are taking, including over-the-counter medications.

Dosing Most thyroid hormone medications are taken once daily, usually in the morning. If you miss a dose of your thyroid hormone medication, take it as soon as possible. If it is almost time for the next dose, do not take the dose you forgot, just continue with your regular schedule; never take a double dose. Call your doctor if you miss two or more doses.

It’s important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with levothyroxine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking levothyroxine, to make sure that the combination is safe.

Certain medicines can interfere with the blood tests that you have to check your thyroid hormone levels (thyroid function tests). It’s important to tell your doctor all the medicines you have been taking both before and at the time of your blood tests.

Avoid taking any of the following medicines at the same time of day as your levothyroxine. This is because they may decrease the amount of levothyroxine that’s absorbed from your gut and so could make it less effective. The occasional dose is unlikely to be a problem, but if you take them together all the time, this may mean that your levothyroxine doesn’t work:

  • antacids
  • calcium supplements (these should not be taken for at least two hours after levothyroxine; be aware that some multivitamin and mineral supplements contain calcium)
  • cimetidine
  • colesevelam (levothyroxine should be taken at least four hours before or after this)
  • colestilan (levothyroxine should be taken at least one hour before or three hours after this)
  • colestipol and colestyramine (levothyroxine should be taken at least one hour before or four to six hours after taking these)
  • iron supplements taken by mouth, eg ferrous sulphate (do not take within two hours of taking levothyroxine)
  • lanathanum (do not take within two hours of taking levothyroxine)
  • orlistat (eg Xenical)
  • polystyrene sulfonate resins
  • sevelamer
  • sucralfate.

Related Story

Levothyroxine may increase the anti-blood-clotting effect of warfarin. If you’re taking levothyroxine with warfarin your blood-clotting time (INR) should be regularly monitored, particularly after any changes in your levothyroxine dose. Your dose of warfarin may need to be decreased otherwise it may increase the risk of bleeding.

The following medicines can affect your thyroid hormones. Your levothyroxine dose may need adjusting if you start or stop treatment with one of these while you’re taking levothyroxine:

  • amiodarone
  • antiepileptic medicines such as phenytoin, carbamazepine and primidone
  • barbiturates such as amobarbital or phenobarbital
  • oestrogens, for instance in the contraceptive pill or HRT
  • rifampicin.

If you’re taking digoxin, theophylline or aminophylline your dose may need to be gradually increased as your thyroid function returns to normal.

More information about levothyroxine

  • What is levothyroxine used for and how does it work?
  • Who can and can’t take levothyroxine?
  • Can I take levothyroxine while pregnant or breastfeeding?
  • What should I know before taking levothyroxine?
  • How do I take levothyroxine?
  • What are the side effects of levothyroxine?

Last updated: 01.04.2019

Helen Marshall, BPharm, MRPharmS Helen Marshall, BPharm, MRPharmS A UK registered pharmacist with a background in hospital pharmacy.


What should I discuss with my healthcare provider before taking levothyroxine?

Levothyroxine should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants.

Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However, you may not be able to take this medicine if you have certain medical conditions. Tell your doctor if you have:

  • an untreated or uncontrolled adrenal gland disorder;
  • a thyroid disorder called thyrotoxicosis; or
  • symptoms of a heart attack (chest pain or heavy feeling, pain spreading to the jaw or shoulder, nausea, sweating, general ill feeling).

Tell your doctor if you have ever had:

  • a thyroid nodule;
  • heart disease, a blood clot, or a blood-clotting disorder;
  • diabetes (insulin or oral diabetes medication doses may need to be changed when you start taking levothyroxine);
  • kidney disease;
  • anemia (lack of red blood cells);
  • osteoporosis, or low bone mineral density;
  • problems with your pituitary gland; or
  • any food or drug allergies.

Tell your doctor if you have recently received radiation therapy with iodine (such as I-131).

If you become pregnant while taking levothyroxine, do not stop taking the medicine without your doctor’s advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby. Your dose needs may be different during pregnancy.

Tell your doctor if you are breast-feeding. Your dose needs may be different while you are nursing.

Do not give this medicine to a child without medical advice. Tirosint is not approved for use by anyone younger than 6 years old.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Levothyroxine oral is taken by mouth. Levothyroxine injection is given as an infusion into a vein. Levothyroxine is usually given by injection only if you are unable to take the medicine by mouth.

Levothyroxine oral works best if you take it on an empty stomach, 30 to 60 minutes before breakfast. Follow your doctor’s dosing instructions and try to take the medicine at the same time each day.

Swallow the tablet or capsule whole, with a full glass (8 ounces) of water. The levothyroxine tablet may dissolve very quickly and could swell in your throat.

Levothyroxine doses are based on weight in children. Your dose needs may change if you gain or lose weight.

It may take several weeks before your body starts to respond to levothyroxine. Keep using this medicine even if you feel well. You may need to use levothyroxine for the rest of your life.

You may need frequent medical tests. Tell any doctor, dentist, or surgeon who treats you that you are using levothyroxine.

Store at room temperature away from moisture and heat.



Therapeutic recommendations are made based only in the review of the available literature concerning a relatively large number of patients, most of them children. Acute levothyroxine overdose is much more common in children compared to adolescents and adults. Therapeutic options are related to the time elapsed after the ingestion of a large number of tablets of L-thyroxine and the actual beginning of emergency therapy (Table 3). Acute massive doses of L-thyroxine typically have a mild clinical course that can be controlled by activated charcoal, or possibly cholestyramine, propranolol, dexamethasone, and supporting measures, with close medical evaluation. Rarely critical cardiac conditions, coma, seizures will follow massive doses of L-Thyroxine.

If more than a few hours of ingestion of LT-4 tablets have elapsed, most probably the tablets have travelled from the gastric cavity to duodenum. Moreover, gastric lavage is difficult to conduct in small children. One way to confirm the presence of LT-4 tablets in the gastric cavity is endoscopy, easily conducted in many hospitals and emergency rooms. LT-4 tablets are dissolved by the gastric juice, but there are no data about the rate of dissolution of a large number of tablets of LT-4. Most probably LT-4 would not be entirely dissolved by the gastric juice and may not be absorbed in the duodenum (normally about 10-15%) but would be absorbed in the jejuno-ileum (normally about 53% of absorption of LT4).

Emetics both local (Ipecac) or central agents (apomorphine) should be avoided.

Administration of activated charcoal is a common practice in many drug overdoses and is an agent that can prevent absorption of several drugs from the gastro-intestinal system. However, in many reports repeated doses of activated charcoal were ineffective in accelerating the elimination of levothyroxine, probably due to high uptake in the duodenum and jejuno-ileum.

Hemoperfusion using activated charcoal is a rather complicated procedure but has been reported to be highly effective in decreasing total serum levels. It should be reserved for adult patients with severe intoxication by very large doses of thyroxine and the same applies to plasmapheresis which has been seldom used.

Cholestyramine, an ion-exchange resin (Questran ®), can be administered in the usual dose of 4 grams every 8 hours orally. This drug binds thyroxine and enhances its elimination.

Glucocorticoids (Dexamethasone 4 mg orally) decrease the conversion of LT4 to T3, the active hormone. Sodium Ipodate (oral cholecystographic agent) has also been used for blocking the conversion of LT4 to T3, but it is no longer generally available.

Beta-blockers such as propranolol, are useful to ameliorate the metabolic effects of thyroid hormone, mostly on the cardiac system (controlling tachycardia, preventing arrhythmias). Seizures may be treated with phenytoin and phenobarbital. Propylthiouracil (PTU) might be used for blocking the conversion of T4 to T3 but may have very limited usefulness in the presence of a large load of LT4.

Hemodialysis has been used in severe cases, but it is probably of limited value since both T3 and T4 are highly protein-bound.



Gastric lavage (within hours of ingestion).
Emetic agents (not advised)
Propranolol (10-40 mg 3 times daily)
Activated Charcoal (1g/kg p.o.)
Dexamethasone (4 mg p.o. daily)
Sodium ipodate, if available
Cholestyramine (4g every 8h p.o.)
Propylthiouracil (PTU) (May inhibit conversion of T4>T3)
Activated charcoal hemoperfusion
Plasmapheresis (seldom necessary)
Hemodialysis (probably of limited value)
Thyroid storm: demands treatment in an Intensive Care Unit.

Ask the experts

I had my thyroid removed and have been using Synthroid for almost 30 years with no problem. What foods or vitamins (for example iron) interfere with the absorption of Synthroid?

Doctor’s response

Aluminum and magnesium containing antacids, calcium carbonate, simethicone, or sucralfate and iron-containing compounds may decrease the absorption of Synthroid; so you should not take these medications within four hours of taking Synthroid. Agents that bind cholesterol such as cholestyramine have the same effect and should also not be taken apart from the Synthroid.

Antidepressants may increase the effects of Synthroid, and the dosage may need to be adjusted.

In regard to foods and herbs, while nothing is off limits in most cases, it is reasonable to limit intake of goitrogenic foods (for example, asparagus, cabbage, peas, turnip greens, broccoli, spinach, brussel sprouts, lettuce, soybeans). Soybean flour (infant formula), cottonseed meal, walnuts, and dietary fiber may also decrease absorption of Synthroid from the GI tract.

While this is not a complete list, it gives you an idea of interactions you may need to consider. For these reasons it is recommended that thyroid medication be taken on an empty stomach 30-60 minutes before meals or at least three hours afterward.

Levothyroxine—Is Morning Still the Best Time to Take It?

With Angela M. Leung, MD, and Amy Hess-Fischl, MS, RDN, CDE

It has long been known that many foods and medications – including calcium supplements, soy, and iron—interfere with the absorption of oral levothyroxine in the body.1 The plot thickens. For the first time, drinking cow’s milk is demonstrated to reduce absorption of levothyroxine,2 according to a study published in the journal Thyroid.

Levothyroxine is one of the most commonly prescribed medications in the US.3 The findings from this prominent team of researchers at the UCLA David Geffen School of Medicine in California are particularly significant since patients are typically instructed to take levothyroxine an hour before breakfast, a meal that commonly includes dairy.

“Changes in the amount of levothyroxine absorbed can lead to changes in thyroid blood tests used to monitor the appropriateness of its dose,” says lead author Angela M. Leung, MD, MSc, assistant professor of medicine at the UCLA David Geffen School of Medicine.

Treatment for hypothyroid must be timed to avoid milk.

Dairy Reduces Levothyroxine Concentration

The study examined 10 healthy subjects with normal thyroid function to assess whether consuming cow’s milk has a direct effect on levothyroxine absorption.2

Following an overnight fast, serum total thyroxine (TT4) concentrations were measured at baseline and at 1, 2, 4, and 6 hours after the participants took 1000 μg of oral levothyroxine alone or when co‐administered with 12 ounces of 2% milk.

Results showed that the TT4 concentrations were significantly lower when levothyroxine was taken at the same time as the milk as compared to levothyroxine alone.2 Also, peak serum TT4 concentrations dropped significantly when cow’s milk was co‐administered with levothyroxine than with the levothyroxine alone.

The researchers believe that both the calcium content of the milk and the presence of protein might directly interfere with the proper and full absorption of levothyroxine, complicating the management of hypothyroid.2

“Our results show that calcium-rich foods should be consumed apart from thyroid hormone medication, as much as possible,” Dr. Leung tells EndocrineWeb. “This will help ensure that thyroid blood tests remain constant, thus decreasing the need for potentially unnecessary changes in the dose of thyroid replacement needed to manage your hypothyroidism.”

Calcium-rich foods including cow’s milk, yogurt, cheeses (eg, ricotta, cottage, cheddar, American) and ice cream and frozen yogurt. Also, non-dairy milk like those made from almond, soy, and rice, which are fortified with calcium.4

Worth Considering a Bedtime Switch?

Typically, patients are advised to take their levothyroxine first thing in the morning, at least 30 minutes but preferably an hour before eating, on an empty stomach and with only water.5 The goal is to achieve consistency in taking the medication to avoid fluctuations in thyroid levels and variable control of symptoms.

But for patients who may want to add milk to their morning coffee or cereal, there are alternative dosing strategies, including taking levothyroxine at night.

While not all patients may be candidates for bedtime administration, those who have a consistent sleep routine and don’t take other medications before bed might consider making this switch.

Of course, before you make any change in the timing of when you take your levothyroxine, you should speak to your doctor. And, it’s important to realize that there must be four hours between your last meal or snack when you plan to take your levothyroxine at bedtime. If you are a nighttime eater, this is likely not a good change for you to make.

Scheduling Timing for Multiple Medications to Avoid Interactions

Another point in planning for bedtime dosing of your levothyroxine is other medications. Ideally, levothyroxine should be the only medication taken at bedtime. Just as with morning dosing, it is best to avoid co-administration with other medications such as statins, blood pressure drugs, and metformin.

If you must take other medications that must be taken in the evening, consider adjusting the timing of these medications so you take them with dinner, leaving four hours afterward so you can take the levothyroxine at bedtime.

Close monitoring of your thyroid levels and any symptoms you notice will help assure that your thyroid labs remain within acceptable reference ranges.

Determine When Taking Levothyroxine is Best for You

“We have plenty of evidence that taking levothyroxine with a meal decreases its absorption and may lead to variability in TSH levels,” says Amy Hess-Fischl, MS, RD, LDN, BC-ADM, CDE, program coordinator for the Teen and Adolescent Diabetes Transition Program at the University of Chicago’s Kovler Diabetes Center.

“For that reason, it’s recommended to wait 30-60 minutes after taking the thyroid hormone before you have breakfast, particularly for those with thyroid cancer, pregnant women, and those sensitive to thyroid fluctuations.”

“What this study proves is that calcium does affect absorption of levothyroxine, making it inadvisable to take with cow’s milk at the same time,” says Ms. Hess-Fischl.

“For practicality’s sake, patients need to find a schedule to take their levothyroxine at a time that will not be affected by meals – some examples would be right when they get up and wait at least 30-60 minute, or plan to take it four hours after they finish eating for the night, if they are having calcium-containing foods such as milk or ice cream,” she tells EndocrineWeb.

“One thing to say up front is that the drug label on levothyroxine says not to eat or drink for 60 minutes before taking the drug in the morning,” says Anne Cappola, MD, professor of medicine in the division of Diabetes, Endocrinology and Metabolism at the Perelman School of Medicine at the University of Pennsylvania. She notes that since people tend to continue to eat after dinner, scheduling a dose of levothyroxine in the evening can be as problematic as taking it first thing in the morning.

“It’s also easier to forget to take the medication in the evening,” she tells EndocrineWeb.

Dr. Cappola also points out that the research brings into question what other foods and dietary substances aside from milk, soy, and iron that have yet to be studied that may also interfere with levothyroxine.

Since eating food later in the evening is likely to promote weight gain,6 this is yet another reason to eat more heavily earlier in the day, according to research presented at ENDO 2018, the 100th Annual Meeting of the Endocrine Society.

Updated on: 04/19/18 Continue Reading Big Breakfast Beats Traditional 6-Meal Diabetes Diet

A recent study assessed thyroidstimulating hormone (TSH) and levothyroxine dosage in 5426 outpatients who had been prescribed levothyroxine, along with drugs that can impair levothyroxine absorption (ie, antacids, iron, sucralfate, cholestyramine, orlistat, sevelamer, and proton pump inhibitors) or drugs that can affect levothyroxine metabolism (carbamazepine, phenobarbital, phenytoin).1 As expected, the TSH level significantly increased after the interacting drugs were initiated, and the subsequent levothyroxine dosage was increased, as well. These findings are consistent with drug–drug interactions that reduce levothyroxine serum concentrations, leading to a compensatory increase in TSH level and the need to increase levothyroxine dosage. This study has the advantage of a large sample size, and it certainly suggests that these interacting drugs may have a clinically important effect on levothyroxine serum concentrations. Nonetheless, the effect of individual drugs on levothyroxine cannot be determined because so many different drugs were studied and the results were lumped together.
Drugs that Impair Levothyroxine Absorption
A number of drugs have been shown to impair the absorption of levothyroxine; these drugs include calcium carbonate, aluminum- containing antacids, sucralfate, iron supplements, cholestyramine, sevelamer, and, possibly, ciprofloxacin, raloxifene, and orlistat.2-5 The magnitude of virtually all drug interactions tends to vary substantially from one individual to another, and the same should be expected with these interactions. In one study on the effect of long-term calcium carbonate therapy in 20 hypothyroid patients stabilized on levothyroxine, the TSH level increased in 13 patients (in 4, above the normal range), was unchanged in 4 patients, and decreased in 3 patients.5 This is probably more variable than some other absorption interactions, in which the binding is strong enough to dramatically reduce the absorption of the affected drug in virtually every patient (eg, ciprofloxacin with aluminum hydroxide).
One factor that probably contributes to the variability of levothyroxine drug–drug interactions is that some individuals are completely dependent on exogenous levothyroxine (eg, following total thyroidectomy) while others have varying degrees of residual thyroid function. Those with some thyroid function may also have varying degrees of feedback stimulation of endogenous thyroid release via thyroidreleasing hormone and TSH.
Proton pump inhibitors (PPIs) have also been reported to reduce levothyroxine absorption, presumably, through an increase in gastric pH, thus reducing dissolution of the levothyroxine tablets. The bulk of evidence suggests that PPIs reduce levothyroxine absorption,2-4,6 although one small study failed to find an interaction between levothyroxine and omeprazole.7 In the outpatient study cited in the introduction, almost 70% of the interacting drugs were PPIs. One study found that replacing levothyroxine tablets with an oral solution improved levothyroxine absorption in the presence of PPIs.8
A variety of medications can inhibit the absorption of levothyroxine, probably by binding with levothyroxine in the gut. It is rarely necessary to avoid binding agents in patients taking levothyroxine, so if the patient needs to receive the binding agent, the following precautions can minimize the risk of an adverse outcome (note: the first 2 bullet points do not apply to proton pump inhibitors because they probably do not bind levothyroxine):

  • Administer levothyroxine at least 2 hours before or 4 hours after the binding agent.
  • Keep the interval between the levothyroxine and binding agent as constant as possible.
  • Monitor the TSH level and watch for clinical evidence of a reduced levothyroxine effect.
  • If the binding agent is discontinued or its dosage changed, or if the interval between the levothyroxine and binding agent is changed, monitor the TSH level, and watch for an altered levothyroxine response.

Drs. Horn and Hansten are both professors of pharmacy at the University of Washington School of Pharmacy. For an electronic version of this article, including references, if any, visit

  1. Trifiro G, Parrino F, Sultana J, et al. Drug interactions with levothyroxine therapy in patients with hypothyroidism: observational study in general practice. Clin Drug Invest. 2015;35(3):187-195.
  2. Irving SA, Vadiveloo T, Leese GP. Drugs that interact with levothyroxine: an observationalstudy from the Thyroid Epidemiology, Audit and Research Study (TEARS). Clin Endocrinol (Oxford). 2015;82(1):136-141.
  3. Liwanpo L, Hershman JM. Conditions and drugs interfering with thyroxine absorption. Best Pract Res Clin Endocrinol Metab. 2009;23(6):781-792.
  4. Benvenga S. When thyroid hormone replacement is ineffective? Curr Opin Endocrinol Diabetes Obes. 2013;20(5):467-477.
  5. Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA. 2000;283(21);2822-2825.
  6. Sachmechi I, Reich DM, Aninyei M, Wibowo F, Gupta G, Kim PJ. Effect of proton pump inhibitors on serum thyroid-stimulating hormone level in euthyroid patients treated with levothyroxine for hypothyroidism. Endocr Pract. 2007;13(4):345-349.
  7. Abi-Abib Rde C, Vaisman M. Is it necessary to increase the dose of levothyroxine in patients with hypothyroidism who use omeprazole? Arq Bras Endocrinol Metabol. 2014;58(7):731-736.
  8. Vita R, Saraceno G, Trimarchi F, Benvenga S. Switching levothyroxine from the tablet to the oral solution formulation corrects the impaired absorption of levothyroxine induced by proton-pump inhibitors. J Clin Endocrinol Metab. 2014;99(12):4481-4486.

About the author

Leave a Reply

Your email address will not be published. Required fields are marked *