Fever

Overview

What is a fever?

A fever is a higher-than-normal body temperature. It’s a sign of your body's natural fight against infection.

  • For adults, a fever is when your temperature is higher than 100.4°F.
  • For kids, a fever is when their temperature is higher than 100.4°F (measured rectally); 99.5°F (measured orally); or 99°F (measured under the arm).

The average normal body temperature is 98.6° Fahrenheit (or 37° Celsius). When you or your child’s temperature rises a few degrees above normal, it’s a sign that the body is healthy and fighting infection. In most cases, that’s a good thing.

But when a fever rises above 102°F it should be treated at home and, if necessary, by your healthcare provider if the fever doesn’t go down after a few days.

What do I do when my child has a fever?

With most cases, a slight fever isn’t a cause for concern with children. A low fever can make a child uncomfortable, it isn’t unusual for them to seem unaffected, still playful and eating and drinking normally, though maybe a bit more tired. Their fever should resolve in a few days.

With higher fevers, call your child’s healthcare provider if:

  • Your child’s fever lasts more than five days.
  • It’s higher than 104°F.
  • The fever is not reduced by medications such as ibuprofen or acetaminophen. (Do not give a child under 17 aspirin due to the risk of Reye's syndrome.)
  • You are concerned that the child isn’t behaving in their usual way, or anything else makes you uncomfortable with their fever or illness.

Some children have a frightening side effect to fever called febrile seizures. This happens in 2% to 4% of children under age 5. Some seizures cause jerking movements, or it may look like your child has passed out. When this happens put your child on their side, do not put anything in their mouth and call 911 if the seizure lasts more than five minutes and/or the child’s lips turn blue.

If it lasts less than five minutes, notify your healthcare provider and go out and get medical attention right away.

What are symptoms of a fever?

The main symptoms of a fever include:

  • Elevated temperature (above 100.4°).
  • Chills, shivering, shaking.
  • Body aches and headaches.
  • Fatigue (tiredness).
  • Intermittent or constant sweating.
  • Flushed complexion or hot skin.

Possible Causes

What causes a fever?

A fever has many causes and can be a symptom of almost any illness. Among the most common are:

However, if you or your child are experiencing a higher-than-normal body temperature and no other symptoms of illness, don’t assume something is wrong. A person's body temperature changes throughout the day and varies with many normal activities and emotions.

For example, stress, excitement, heavy clothing, food, certain medications, a menstrual cycle and exercise can all raise body temperature. Also, children tend to have a slightly higher body temperature than adults.

Care and Treatment

What is the best way to measure body temperature?

The best way to measure body temperature is using a thermometer inserted orally, rectally, axillary (under the arm), or by using a special instrument commonly sold in stores that is inserted in the ear and measures the temperature of the eardrum.

Can a fever be treated at home?

If your fever is mild (less than 101°F), then no medical treatment is required. Simply make sure that you drink plenty of fluids (not alcohol) – and get plenty of rest.

For higher temperatures, there are many effective ways to getting your fever under control. The most common way includes medications such as aspirin, acetaminophen and ibuprofen.

If you have a child under age 17 who has a fever, DO NOT give the child aspirin. Aspirin in children may cause Reye's syndrome, a sometime fatal illness. Taking a lukewarm bath (around 98°F) may also help bring the body's temperature down.

When to Call the Doctor

When is a fever cause for concern?

If any of the following situations apply, call a doctor as soon as possible:

  • A fever accompanied by a stiff neck, confusion or irritability.
  • A fever remaining above 103°F (39.5°C) longer than two hours after home treatment.
  • A fever lasting longer than two days.
  • High fever accompanied by rash.
  • Photophobia (irritated by light).
  • Dehydration (less amount of urine, sunken eyes, no tears).
  • Seizures.

Any fever in an adult that goes above 105°F (or 40.5°C) and does not come down with treatment is a life-threatening medical emergency and you should call 911.

Last reviewed by a Cleveland Clinic medical professional on 12/31/2019.

References

  • American Academy of Family Physicians. . Accessed 1/6/2020.Fever (https://familydoctor.org/symptom/fever/?adfree=true)
  • Hague R. Managing the child with a fever. Practitioner. 2015;259(1784):17-21, 2-3.
  • NHS Choices. Accessed 1/6/2020.Fever in children. (http://www.nhs.uk/conditions/feverchildren/Pages/Introduction.aspx)
  • Merck Manual. Accessed 1/6/2020.Fever. (https://www.merckmanuals.com/professional/infectious-diseases/biology-of-infectious-disease/fever)

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