Fever: Symptoms, Causes, and Treatment

Fever occurs when your body temperature rises to about 99 degrees Farentheit or higher because of an illness. A fever is an anti-inflammatory response and a reaction to foreign invaders in the body. A fever's purpose is to help the body fight off bacteria and viruses. Most fevers are treatable at home, but there are some that require medical attention.

This article covers the symptoms and types of fever, causes of fever, how to treat fever, and when to get help.

Woman with a fever

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Symptoms of Fever

In addition to a temperature of about 99 degrees, a fever can also include the following symptoms:

  • Chills and shivers
  • Excessive sweating
  • Fatigue
  • Joint, bone, or back pain
  • Headache
  • Dehydration

In children, symptoms of fever can include:

  • Lower activity levels and staying quiet
  • Fussiness
  • Increased thirst and less hunger
  • Feeling warm

For about 3% of children aged 6 months to 5 years old, seizures called febrile convulsions can occur with a fever. Children who experience febrile convulsions usually outgrow them by 5 years of age.

Causes of Fever

Fever is usually a result of the immune system's fighting off an infection. The most common causes of fever are:

Other causes of fever include:

What Medications Cause Fever?

"Drug fever" is the term for fever that is a side effect of a medication. Drug fever usually disappears soon after the medication is discontinued.

Medications that could cause fever include:

  • Anti-seizure medications
  • H2-blockers, which reduce acid in the stomach
  • Antibiotics
  • Antihistamines

How to Treat Fever

Mild fevers are usually treated at home with:

  • Rest
  • Getting more fluids, which can include drinking soup broth or sucking on ice pops (avoid sports drinks or too much juice)
  • Removing extra clothing or heavy blankets, especially for young children and infants
  • A lukewarm bath after medication

Medications to treat fever include:

  • Over-the-counter (OTC) fever-reducing medications like Tylenol (acetaminophen) or Advil (ibuprofen) taken as advised
  • Aspirin (for adults only)
  • Provider-approved medications for babies under 3 months of age

Complications and Risk Factors Associated with Fever

Fevers require medical attention if they're between 100.4 and 102.2 degrees in children aged 0-24 monthshttps://cms.greenhouse.dotdash.com/edit/6544748 or between 103 and 105 degrees in older children and adults. If left untreated, complications of fever could include:

  • In 2%–5% of children under age 5, febrile seizures can occur with higher fevers
  • Brain damage with fevers of 107 degrees or higher
  • Breathing issues
  • Death

When to See a Healthcare Provider

Call your healthcare provider if a child:

  • Is 3 months or younger and has a rectal temperature of 100.4 degrees or higher
  • Is 3 month olds to 12 month olds and has a fever of 102.2 degrees or higher
  • Is younger than 2 and has a fever lasting longer than 24–48 hours
  • Is older and has a fever lasting 48–72 hours
  • Has a weakened immune system
  • Has other symptoms like a sore throat, cough, or earache
  • Has recently been to another country

Adults should see a healthcare provider if they:

  • Have a fever over 105 degrees
  • Have a fever that lasts longer than 48–72 hours
  • Have new rashes or bruises
  • Have pain when urinating
  • Have a heart problem, lung problem, or sickle cell anemia
  • Have recently been to another country

Seek emergency medical attention for anyone of any age who has a fever and:

  • Can't walk
  • Seems confused
  • Can't be awakened easily (if at all)
  • Has blue lips, nails, or tongue
  • Has a seizure
  • Has breathing difficulty


Fever is a temporary rise in body temperature as it fights off an infection. In addition to a higher temperature, symptoms of fever can include chills, sweating, fatigue, and body pains. Causes of fever include bacterial or viral infections such as the flu or cold, overdressing, autoimmune disorders, and vaccinations. Some medications can also cause fevers.

Treating fever usually includes getting rest and drinking fluids while stabilizing body temperature with lighter clothes and blankets. OTC pain medications like acetaminophen and ibuprofen can also be a part of the treatment.

A Word From Verywell

While having a fever can be disruptive and frustrating, it is a necessary part of fighting off infections. Most fevers are easily treatable with a bit of rest and a lot of fluids. With some time, you'll likely feel like your normal self.

Frequently Asked Questions

  • Why do fevers occur?

    Fevers are usually a response to infections like bacteria or viruses. That's why they occur most often during illnesses like flu, cold, and pneumonia. Fevers can also be a part of autoimmune disorders like lupus or rheumatoid arthritis and conditions that weaken the immune system. At times, a high room temperature or intense emotions can also cause fever, as can medications, including antibiotics, antihistamines, and anti-seizure drugs.

  • When is a fever dangerous?

    While most fevers can be treated at home, some fevers can be dangerous. For babies younger than 3 months, a fever 100.4 degrees requires medical attention, while children 3 months old to 12 months old usually require medical attention at a fever of 102.2 degrees or higher. For adults or older children, a fever of 103–105 degrees might require urgent care. A fever of any temperature that persists for a week is likely something that requires help from a healthcare provider.

  • What are the most effective ways to treat fever?

    Most fevers only require rest and fluids, however, over-the-counter medications can also help. Wearing lighter clothing and avoiding heavy blankets can also help with fever, as can a lukewarm bath after taking medication.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Dall L, Stanford JF. Fever, chills, and night sweats. In: Walker HK, Hall WD, Hurst JW, eds. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Butterworths; 1990.

  2. Stanford Medicine. Fever in children.

  3. Queensland Health. What is a fever: When should you worry about a high temperature?

  4. Medline Plus. Fever.

  5. Nemours Children's Health System. Fevers.

  6. Penn Medicine. Fever.

  7. Patel RA, Gallagher JC. Drug feverPharmacotherapy. 2010;30(1):57-69. doi: 10.1592/phco.30.1.57

  8. Hiraide A, Yoshioka T, Ohshima S. IgE-mediated drug fever due to histamine H2-receptor blockersDrug Saf. 1990;5(6):455-457. doi:10.2165/00002018-199005060-00006.

  9. Hackensack Meridian Health. When to seek care for a fever.

  10. National Institute of Neurological Disorders and Stroke. Febrile seizures fact sheet.

  11. Geddes L. The fever paradoxNew Sci. 2020;246(3277):39-41. doi: 10.1016/S0262-4079(20)30731-4

By Neha Kashyap
Neha is a New York-based health journalist who has written for WebMD, ADDitude, HuffPost Life, and dailyRx News. Neha enjoys writing about mental health, elder care, innovative health care technologies, paying for health care, and simple measures that we all can take to work toward better health.