Fever for 8 days

What Causes a Persistent Low-Grade Fever and How Is It Treated?

Viral infections, like the common cold, are the most common cause of a persistent low-grade fever, but there are other less common causes to consider.

Respiratory infections

Your body naturally raises its body temperature to help kill the bacteria or virus causing an infection. Colds or the flu are caused by viruses. Colds in particular can cause a low-grade fever that lasts more than a few days.

Other symptoms of a cold include:

  • stuffy or runny nose
  • sore throat
  • sneezing
  • cough
  • fatigue
  • lack of appetite

Viral pneumonia and bronchitis are two other types of respiratory infections that can also cause a low-grade fever. Along with a fever, chills, and a sore throat, pneumonia and bronchitis come with a cough that persists for weeks.

In children, it’s common to experience “back-to-back” viral infections. This can make it seem like the fever is lasting longer than it should be.

Treatment for viral infections involves rest and fluids until your body takes care of the infection. You can take acetaminophen for reducing a fever if your symptoms are really bothersome. Fevers are important in helping your body fight off certain infections, so sometimes it’s best to wait it out.

If the infection is more serious, your doctor may prescribe antibiotics, antiviral drugs, or other medications to help treat the infection.

Urinary tract infections (UTIs)

Persistent fever can signal a hidden urinary tract infection in both children and adults. A UTI is caused by a bacterial infection. Other symptoms include pain and burning while urinating, frequent urination, and bloody or dark urine.

A doctor can examine a sample of urine under a microscope to diagnose a UTI. Treatment involves a course of antibiotics.


A low-grade fever can occur about 7 to 10 days after starting a new medication. This is sometimes called drug fever.

Drugs associated with a low-grade fever include:

  • beta-lactam antibiotics, such as cephalosporins and penicillins
  • quinidine
  • procainamide
  • methyldopa
  • phenytoin
  • carbamazepine

If your fever is related to a medication, your doctor may adjust your dosage or recommend a different drug. The fever should disappear once the medication is stopped.

Teething (infants)

Teething usually occurs between 4 and 7 months of age. Teething can occasionally cause mild irritability, crying, and a low-grade fever. If the fever is higher than 101°F, it’s not likely caused by teething and you should bring your infant to see a doctor.


A persistent fever can be caused by chronic, emotional stress. This is called a psychogenic fever. Psychogenic fevers are most common in young women and people with conditions often exacerbated by stress, such as chronic fatigue syndrome and fibromyalgia.

Fever-reducing drugs like acetaminophen don’t actually work against fevers caused by stress. Instead, anti-anxiety drugs are the therapy used to treat a psychogenic fever.


Tuberculosis (TB) is a highly infectious disease caused by a bacterium called Mycobacterium tuberculosis. Though TB is more common in developing countries, thousands of cases are reported in the United States each year.

The bacteria can remain inactive in your body for years and cause no symptoms. When your immune system is weakened, however, TB can become active.

Symptoms of active TB include:

  • coughing up blood or sputum
  • pain with coughing
  • unexplained fatigue
  • fever
  • night sweats

TB can cause a persistent, low-grade fever, especially at night, which can result in night sweats.

A doctor can use a test called the purified protein derivative (PPD) skin test to determine if you’re infected with the TB bacteria. People diagnosed with active TB disease have to take several medications for six to nine months in order to cure the infection.

Autoimmune diseases

Body temperature has been found to be elevated in some people with chronic autoimmune disease, such as multiple sclerosis and rheumatoid arthritis.

In one study, researchers learned that participants with a form of MS called relapsing MS who complained of fatigue also had a low-grade fever.

A low-grade fever is also a common symptom of RA. It’s thought to be caused by inflammation of the joints.

Diagnosing RA and MS can take time and may require multiple lab tests and diagnostic tools. If you’ve already been diagnosed with RA or MS, your doctor will want to first rule out another viral or bacterial infection as the potential cause of your fever.

In case of RA- or MS-related fever, a doctor will likely recommend that you drink plenty of fluids, remove extra layers of clothing, and take a nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen until the fever passes.

Thyroid issues

Subacute thyroiditis is an inflammation of the thyroid gland. It can cause a low-grade fever in some cases. Thyroiditis may be caused by infection, radiation, trauma, autoimmune conditions, or medications.

Other symptoms include:

  • muscle pain
  • fatigue
  • tenderness near the thyroid gland
  • neck pain that often radiates up to the ear

A doctor can diagnose thyroiditis with an examination of the neck and a blood test that measures thyroid hormone levels.


Certain cancers — lymphomas and leukemias in particular — can cause a persistent and unexplained low-grade fever. Keep in mind that a cancer diagnosis is rare and a fever is a nonspecific symptom of cancer. Having a persistent fever doesn’t usually mean you have cancer, but it can alert your doctor to run certain tests.

Other common symptoms of leukemia or lymphoma include:

  • chronic fatigue
  • bone and joint pain
  • enlarged lymph nodes
  • headaches
  • unexplained weight loss
  • night sweats
  • weakness
  • breathlessness
  • loss of appetite

Depending on the type and stage of the cancer, a doctor may recommend a combination of chemotherapy, radiation, surgery, or other treatments.


Is this your child’s symptom?

  • An abnormal high body temperature
  • Fever is the only symptom. Your child has a true fever if:
  • Rectal (Bottom), Ear or Forehead temperature: 100.4° F (38.0° C) or higher
  • Oral (Mouth) temperature: 100° F (37.8° C) or higher
  • Under the arm (Armpit) temperature: 99° F (37.2° C) or higher
  • Caution: Ear temperatures are not accurate before 6 months of age
  • Caution: Forehead temperatures must be digital. Forehead strips are not accurate.

Causes of Fever

  • Overview. Almost all fevers are caused by a new infection. Viruses cause 10 times more infections than bacteria. The number of germs that cause an infection are in the hundreds. Only a few common ones will be listed.
  • Viral Infections. Colds, flu and other viral infections are the most common cause. Fever may be the only symptom for the first 24 hours. The start of viral symptoms (runny nose, cough, loose stools) is often delayed. Roseola is the most extreme example. Fever may be the only symptom for 2 or 3 days. Then a rash appears.
  • Bacterial Infections. A bladder infection is the most common cause of silent fever in girls. Strep throat is also a common cause of unexplained fever.
  • Sinus Infection. This is a problem caused by a cold. The main symptom is the return of fever after it has been gone for a few days. The sinus congestion also changes to sinus pain. Color of nasal discharge is not very helpful for making this diagnosis.
  • Vaccine Fever. Fever with most vaccines begins within 12 hours. It lasts 2 to 3 days. This is normal and harmless. It means the vaccine is working.
  • Newborn Fever (Serious). Fever that occurs during the first 3 months of life can be serious. All of these babies need to be seen as soon as possible. The fever may be due to sepsis (a bloodstream infection). Bacterial infections in this age group can get worse quickly. They need rapid treatment.
  • Meningitis (Very Serious). A bacterial infection of the membrane that covers the spinal cord and brain. The main symptoms are a stiff neck, headache and confusion. Younger children are lethargic or so irritable that they can’t be consoled. If not treated early, can suffer brain damage.
  • Overheated. The fever is usually low grade. Can occur during heat waves or from being overdressed. The temp becomes normal in a few hours after moving to a cooler place. Can also occur during hard exercise. Fever goes away quickly with rest and drinking extra fluids.
  • Not Due to Teething. Research shows that “getting teeth” does not cause fevers.

Fever and Crying

  • Fever on its own shouldn’t cause much crying.
  • Frequent crying in a child with fever is caused by pain until proven otherwise.
  • Hidden causes can be ear infections, kidney infections, sore throats and meningitis.

Roseola: Classic Cause of Unexplained Fever in Young Children

  • Most children get Roseola between 6 months and 3 years of age.
  • Cause: human herpes virus 6
  • Rash: pink, small, flat spots on the chest and stomach. Rash is the same on both sides of the body.
  • Then spreads to the face.
  • Classic feature: 2 or 3 days of high fever without a rash or other symptoms.
  • The rash starts 12 to 24 hours after the fever goes away.
  • The rash lasts 1 to 3 days.
  • By the time the rash appears, the child feels fine.

Normal Temperature Range

When to Call for Fever

Call 911 Now

  • Not moving or too weak to stand
  • Can’t wake up
  • Trouble breathing with bluish lips or face
  • Purple or blood-colored spots or dots on skin
  • You think your child has a life-threatening emergency

Call Doctor or Seek Care Now

  • Trouble breathing
  • Great trouble swallowing fluids or spit
  • Not alert when awake (“out of it”)
  • Acts or talks confused
  • Age less than 12 weeks old with any fever. Caution: do NOT give your baby any fever medicine before being seen.
  • Fever over 104° F (40° C)
  • Shaking chills (shivering) lasting more than 30 minutes
  • Nonstop crying or cries when touched or moved
  • Won’t move an arm or leg normally
  • Dehydration suspected. No urine in more than 8 hours, dark urine, very dry mouth and no tears.
  • Pain or burning when passing urine
  • Weak immune system. Examples are: sickle cell disease, HIV, cancer, organ transplant, taking oral steroids.
  • Your child looks or acts very sick
  • You think your child needs to be seen, and the problem is urgent

Call Doctor Within 24 Hours

  • Age 3-6 months old with fever
  • Age 6-24 months old with fever that lasts more than 24 hours. There are no other symptoms (such as cough or diarrhea).
  • Fever lasts more than 3 days
  • Fever returns after being gone more than 24 hours
  • Recent travel outside the country to high risk area
  • You think your child needs to be seen, but the problem is not urgent

Call Doctor During Office Hours

  • You have other questions or concerns

Self Care at Home

  • Fever with no other symptoms and your child acts mildly ill

Seattle Children’s Urgent Care Locations

If your child’s illness or injury is life-threatening, call 911.

Care Advice for Fever

  1. What You Should Know About Fever:
    • Having a fever means your child has a new infection.
    • It’s most likely caused by a virus.
    • You may not know the cause of the fever until other symptoms develop. This may take 24 hours.
    • Most fevers are good for sick children. They help the body fight infection.
    • Use the ranges below to help put your child’s level of fever into perspective:
    • 100° – 102° F (37.8° – 39° C) Low grade fever: helpful, good range. Don’t treat.
    • 102° – 104° F (39 – 40° C) Average fever: helpful. Treat if causes discomfort.
    • Over 104° F (40° C) High fever: causes discomfort, but harmless. Always treat.
    • Over 106° F (41.1° C) Very high fever: important to bring it down. Rare to go this high.
    • Over 108° F (42.3° C) Dangerous fever: fever itself can be harmful.
  2. Treatment for All Fevers – Extra Fluids
    • Fluids alone can lower the fever. Reason: being well-hydrated helps the body give off heat through the skin.
    • Offer your child extra water or other fluids by mouth. Cold fluids are better. Until 6 months old, only give extra formula or breastmilk.
    • For all children, dress in 1 layer of light weight clothing, unless shivering. Reason: also helps heat loss from the skin.
    • Caution: if a baby under 1 year has a fever, never overdress or bundle up. Reason: babies can get over-heated more easily than older children.
    • For fevers 100°-102° F (37.8° – 39°C), fever meds are rarely needed. Fevers of this level don’t cause discomfort. They do help the body fight the infection.
    • Exception: if you feel your child also has pain, treat it.
  3. Fever Medicine:
    • Fevers only need to be treated with medicine if they cause discomfort. Most often, that means fevers above 102° F (39° C). Also use for shivering (shaking chills). Shivering means the fever is going up.
    • For fevers above 102° F (39° C), give an acetaminophen product (such as Tylenol).
    • Another choice is an ibuprofen product (such as Advil).
    • Goal of treatment: Bring the temperature down to a comfortable level. Most often, the fever meds lower the fever by 2° to 3° F (1 – 1.5° C). They do not bring it down to normal. It takes 1 or 2 hours to see the effect.
    • Do not use aspirin. Reason: Risk of Reye syndrome, a rare but serious brain disease.
    • Do not use both acetaminophen and ibuprofen together. Reason: Not needed and a risk of giving too much.
  4. Sponging With Lukewarm Water:
    • Note: Sponging is an option for high fevers, but not required. It is rarely needed.
    • When to Use: Fever above 104° F (40° C) AND doesn’t come down with fever meds. Always give the fever medicine at least an hour to work before sponging.
    • How to Sponge: Use lukewarm water (85 – 90° F) (29.4 – 32.2° C). Sponge for 20-30 minutes.
    • If your child shivers or becomes cold, stop sponging. Other option: You can also make the water warmer.
    • Caution: Do not use rubbing alcohol. Reason: Can cause a coma.
  5. Return to School:
    • Your child can return to school after the fever is gone. Your child should feel well enough to join in normal activities.
  6. What to Expect:
    • Most fevers with viral illnesses range between 101° and 104° F (38.4° and 40° C).
    • They may last for 2 or 3 days.
    • They are not harmful.
  7. Call Your Doctor If:
    • Your child looks or acts very sick
    • Any serious symptoms occur such as trouble breathing
    • Fever goes above 104° F (40° C)
    • Any fever occurs if less than 12 weeks old
    • Fever without other symptoms lasts more than 24 hours (if age less than 2 years)
    • Fever lasts more than 3 days (72 hours)
    • You think your child needs to be seen
    • Your child becomes worse

And remember, contact your doctor if your child develops any of the ‘Call Your Doctor’ symptoms.

Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.

Last Reviewed: 02/01/2020

Last Revised: 03/14/2019

Copyright 2000-2019 Schmitt Pediatric Guidelines LLC.

5 days of fever, now what should I do?

I have used a lot of words to tell you not to worry about fever. Fever is your child’s friend. Don’t go to the ER for fever alone. Don’t buy all the fever myths out there.

When should you be worried? The biggest issue is context. You can read the other posts to see all about that.

Another reason you should be more concerned with fever is if it is lasting more than 5 days. Of course, if you end up with a diagnosis where fever is known to last more then 5 days, no big deal, but otherwise, most fevers should be gone by then.

This situation is called fever without a source.

There are many different definitions of fever without a source but I use: fever greater than 101 for eight days in a child in whom there is no obvious source of the fever through the patient’s story or physical exam.

Because children can often have back-to-back viral infections, it is important that this fever be present daily or near daily. For instance, it doesn’t count if they had fever for 3 days then were better for 2 days and then had fever again for 3 days.

The different things to think about are all over the place and can range from very serious to the “no-big-deal.”

Infections – The most common diagnosis in this instance is “unknown” but the fever goes away on its own. While often not intellectually satisfying (to either me or the parent who wants to know what is going on), this is probably the best outcome for the patient. Most of those are probably viruses for which we don’t have or don’t think to run specific tests. Bacterial infections can also cause long-standing fever.

Rheumatologic – Less commonly, children with prolonged fever can have rheumatologic causes, an example is juvenile rheumatoid arthritis. Often these children will have exam findings like swollen, painful joints or swollen lymph nodes that will help point towards their diagnosis.

Malignancy – Fortunately, this is a very rare cause of prolonged fever but it does happen so we all need to keep it in the back of our mind. The most common type of cancer in children is leukemia.

The workup for fever without a source involves a few things:

  1. Repeat histories and physical exams – Often things are discovered over time.
  2. Preliminary screening labs – Check these in just about all kids with it.
  3. Specific tailored labs and exams – Check some of these based on a child’s story or exam.

Kawasaki disease

One specific cause of fever over five days deserves specific attention. Because many parents are not aware of it and because the diagnosis can be tricky, I thought it deserved its own specific mentions.

Kawasaki disease (KD) is characterized by the characteristic fever over 5 days along with some of the following findings:

  • Swelling or redness of the hands and feet, followed by peeling of the tips of the toes or fingers
  • Red rash all over
  • Redness and crusting of the lips or redness of the tongue (like a strawberry)
  • Severe pink eye
  • Swollen lymph nodes of the neck

One of the other things to note with KD is that these children are very, very irritable. Not kinda irritable, but noticeably irritable even to a pediatrician who hears crying babies and children all day long irritable.

The cause of KD is unknown. There is some evidence to suggest that there might be an infection involved. The symptoms and complications associated with it are a result of inflammation of small to medium sized arteries throughout the body.

The most commonly known complications of KD involve the heart and can be inflammation or the lining or muscles of the heart or dilation of the arteries that supply the heart.

If you suspect your child has KD it is important to seek your doctor’s advice quickly, as it is much easier for your physician to connect the dots when symptoms are present. Blood tests can help confirm the diagnosis and treatment can resolve the symptoms and help to prevent complications.

The good news is that children with Kawasaki’s disease, like the child in the photos with this blog, usually return to normal and don’t suffer complications.

Get to know Justin Smith, M.D.

Justin Smith, M.D., is a pediatrician in Trophy Club and the Medical Advisor for Digital Health for Cook Children’s in Fort Worth, Texas. Dr. Smith is an experienced keynote speaker for a variety of topics including pediatric/parenting topics, healthcare social media and physician leadership. If you are interested in having Dr. Smith present to your conference or meeting, please contact him at [email protected]

He has an active community on both Facebook and Twitter as @TheDocSmitty and writes weekly for Cook Children’s checkupnewsroom.com. He believes that strategic use of social media and technology by pediatricians to connect with families can deepen their relationship and provide a new level of convenience for both of their busy lifestyles. Dr. Smith’s innovative pediatric clinic, a pediatric clinic “designed by you,” open now. Click here to make an appointment, call 817-347-8100.

Research has shown that in 85 to 95% of cases, the specific cause for a fever of unknown origin can eventually be identified after extensive testing, often in a hospital setting. Doctors may need to perform a variety of diagnostic tests to help them determine the exact cause of an unexplained fever. Blood tests, a thorough physical examination, and radiological studies (most commonly a chest x-ray and/or chest and abdominal CT scans) are generally performed as a first step in the investigation of unexplained fever.

About one-third of fevers of unknown origin are caused by infections. Infections are also the most common cause of FUOs in children. Any type of infection, from a self-limiting common cold to HIVdisease, can result in fevers. In certain situations, a person may harbor a fever-producing infection that is not causing any recognizable physical signs or symptoms other than the fever. Microbiology techniques (culturing of body fluids from different sites to identify bacteria, viruses, fungi, or parasites) can sometimes identify an occult (hidden) infection. In other cases, blood tests that measure antibody levels in the blood can confirm whether an infection is present.

But infection does not account for 2 of 3 fevers of unknown origin! Cancers are estimated to cause 20-30% of FUOs. Lymphomas and leukemias are two kinds of cancer that often cause fevers, but any type of malignant tumor can be a source of fever.


Bowel regularity means a bowel movement every day. See Answer

5 truths about fevers in children


The flu, RSV, colds, croup, strep throat, ear infections. They all have one thing in common: they can cause fevers. And as any parent can attest to, it’s often the fever itself that freaks us out more than anything and prompts many parents to call their child’s pediatrician or hustle them off to the emergency room.

Fever is clearly not a parent’s friend.

Or is it?

You might be surprised to know that in most cases, fever is a good thing. And when armed with the truth about fevers, you may just rest a bit easier and handle your child’s fever with ease.

Here are 5 must-knows about fevers. Remember these the next time your little one’s temperature starts to rise:

1. Fever is a symptom, not a disease. Remember, your child’s body is only reacting to illness. That fever is letting you and your child know that they are sick. Consider it a very obvious warning. Time to call it a sick day, drink some fluids, and rest. And by the same token, treating your child’s fever will not suddenly “cure” whatever infection he/she is currently fighting off. Think of it like disabling your car’s “oil change needed” light. Sure, you can turn off that light but it doesn’t negate the fact that your car’s oil still needs changing.

You can suppress that fever, but your child still needs time to rest and recover from her current infection.

2. Expect fever to wax and wane for 3-4 days. Most fevers will naturally persist for a few days before they completely go away. So yes, you can give that acetaminophen or ibuprofen, but expect that fever to bounce back up after a few hours. That’s completely normal.

3. The number on your thermometer is not as important as how your child looks and feels. I think most parents start to get a little panicked when they start seeing 103 and 104 F beeping back at them. But that number has no bearing on the seriousness of your child’s illness. So resist the urge to panic. Give your child a fever reducer to make him more comfortable and stay on top of his hydration. Fevers make the heart beat faster and increases your child’s insensible water loss (fluids lost through the skin and respiratory tract). So keep that water bottle handy.

4. Goal of fever treatment is to help your child feel better, not get rid of the fever altogether. Remember to treat your child, not the number on the thermometer. Surely, when your child’s temp starts rising to 102°F or higher, they may need something to help them feel better. But also remember this: fever reducers will not always normalize your child’s temperature. It may bring it down a couple of degrees. And that’s both perfectly normal and OK. You have succeeded in making your child a little more comfortable during his/her illness.

5. A true fever is a temperature of 100.4°F (38°C) or higher. Children’s temperatures naturally fluctuate throughout the day. So knowing what is a true fever is very important.

Some additional tips for dealing with fevers:

  • Resist the urge to treat at the slightest temperature elevation. Remember, your child’s fever is serving a purpose. So unless you’re dealing with a 102°F or higher fever, let the fever run its course and keep your child comfortable by offering plenty of fluids.
  • Stay calm and realize that when your child spikes a fever, it means his/her body is doing exactly what it’s supposed to be doing: mobilizing the troops (aka activating the immune system) to fight off his/her current infection.

Red flags:

  • Any infant less than 3-months-old with rectal temperature of 100.4°F or greater needs to be seen by his/her pediatrician for evaluation. No matter what.
  • Fever that persists greater than 5 days.
  • Your child just doesn’t look well, is having difficulty breathing or has had a febrile seizure.
  • Your child’s fever is 105°F or higher. While this is not that common, some children can spike high fevers of 105 and 106. And while this is usually not harmful to your child (believe it or not), it still deserves a call to your pediatrician and the right dose of acetaminophen or ibuprofen.

Fever is on our side. It serves a purpose. And it’s not the worst thing about your child being sick. I think it’s that darn cough, the stuffy/runny nose, or vomiting that does us in.

Melissa Arca is a pediatrician who blogs at Confessions of a Dr. Mom.

Image credit: .com


Follow me on Twitter @drClaire

Fevers worry parents; they scare them sometimes. I understand why. After all, fevers can be a sign of something serious — and at the beginning of one, it’s hard to know whether it’s going to turn out to be something serious.

Most of the time, it isn’t serious. Fevers are very common. They are part of how the body fights infection. The average child will get several viral infections a year — which means several fevers. The vast majority of fevers are nothing to worry about, and pass in a day or two.

Sometimes, though, parents should worry. Here are some circumstances when you should be worried about a fever and seek medical attention immediately:

  • If your child is less than 3 months old. While most fevers in newborns turn out just fine, their defenses are still getting up and going and they aren’t very good at telling us what hurts.
  • If the fever is accompanied by a dark rash (small or larger spots, flat or raised) that looks almost like a bruise and doesn’t get paler when you press on it. This can be a sign of a serious infection.
  • If your child is extremely sleepy or extremely irritable. This always worries doctors. Kids are often sleepy and cranky when they get sick. What I’m talking about here is when that sleepiness and crankiness get severe. If you aren’t sure whether your child’s symptoms are severe, call and talk to your doctor (or the person on call).
  • If your child has severe pain, or difficulty moving any part of the body (like the neck).
  • If your child has trouble breathing, or is breathing more quickly or forcefully than usual. It could be a sign of a serious lung infection.
  • If your child has a condition, or is taking a medication, that makes it harder for them to fight infection. It’s important to check in early with your doctor.

It’s also a good idea to call your doctor if:

  • Your child has a fever greater than 102° F (or 39° C). It’s probably nothing serious, but it’s worth checking in with a doctor or nurse to go through things and see if a visit to the office or emergency room makes sense.
  • Your child has a rash with the fever (not like the one described above, for that, go right to the emergency room). It’s most likely nothing to be worried about, but some viruses worry us more than others (like measles, or chicken pox) and some bacterial infections that need antibiotics (like strep throat, or cellulitis) can cause rashes.
  • The fever has lasted more than two to three days. Again, probably nothing to worry about, but worth checking in to be sure.
  • Your child is drinking much less than usual, especially if they are also urinating much less than usual. They may be dehydrated.
  • There is something else that doesn’t seem right to you. Over the years, I’ve learned to trust a parent’s instincts. You know your child better than anyone. Call if you are worried.

If none of this applies, chances are your child has a minor illness and will be just fine. Acetaminophen and ibuprofen can be helpful for making your child more comfortable, although if your child is acting fine and drinking (eating is optional, it’s the drinking that’s key), it might be best to let the fever be and let the body do its job. Make sure your child gets plenty of rest — and TLC.

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