Causes of fever

Woman and baby with a fever

How does fever occur?

Fever occurs when the hypothalamus resets the normal body temperature point to a higher level. Although the body is still working to balance the heat produced with that which it releases, since the set-point is now higher, body temperature rises.1

An increase in body temperature may occur due to various reasons such as release of certain chemicals called cytokines in response to invading microorganisms, cancer cells, or any other foreign matter. It is also in response to the body producing white blood cells and antibodies to protect it from invading foreign matter.2

Common causes of fever

Child with fever

Infectious causes of fever

Any form of infection can cause the body to respond with a fever. These include viral and bacterial infections such as:3,4

Viral infections
  • Common cold
  • Influenza
  • Meningitis
  • Dengue fever
  • Gastroenteritis
Bacterial infections
  • Dysentery
  • Bacterial pneumonia
  • Tuberculosis
  • Urinary tract infections
  • Otitis media (ear infections)
  • Gastroenteritis
  • Meningitis

The above list contains examples of viral and bacterial infections and is not all encompassing.

  • Man with a fever

    While it is more common for a person to develop fever due to infection, there are non-infectious causes of fever, including:1

    Auto-immune diseases
    • Systemic lupus erythematosus
    • Rheumatoid arthritis
    • Leukemias
    • Lymphomas
    Drug induced
    • Sulfa drugs
    • Antiepileptic medications (i.e., phenytoin, carbamazepine)
    • Antiretroviral medicines (for the treatment of HIV)
    • Antiarrhythmic medications (e.g., amiodarone)
    Crystal-induced arthropathies
    • Gout (accumulation of uric acid in the joints)
    • Deep vein thrombosis
    Abdominal conditions
    • Acute pancreatitis
    Central nervous system conditions
    • Stroke (hemorrhagic and ischemic)

    HIV = human immunodeficiency virus.

  • Baby smiling

    Some of the most common causes of fever in children are:5

    • Upper respiratory tract infections
    • Influenza
    • Ear infections
    • Roseola, which is caused by a virus and is associated with a rash
    • Tonsillitis
    • Common childhood illnesses (e.g., chicken pox)
    • After immunizations

    However, contrary to popular belief, teething does not cause fever. There may be a slight increase in temperature during teething due to the irritation of the gums, but it is not high enough to qualify as a fever.6

    This is important to remember as, if a child who is teething also has a fever, then there may be an underlying infection that should be treated.

Understanding fever

Signs and symptoms

Fever overview

Find out the basics about fever.


Signs and symptoms

How do the signs and symptoms of fever present?

Refresh your knowledge on the signs and symptoms of fever, and learn about “red flag” symptoms that indicate when a referral to a doctor is necessary.

Signs and symptoms


What can you recommend to your patients for fever?

Find out more about non-pharmacological and pharmacological treatments for fever in both children and adults.


Learn more

Advil product images

Acute pain and/or fever relief products for adults

Help your adult patients manage their acute pain and fever with the full range of effective and well-studied pain-relieving Advil products.7,8

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Children’s Advil product images

Children’s Advil — helping parents relieve children’s fever and pain

With proven efficacy in different types of pain and a well-established safety profile – you can trust the pain relief of ibuprofen in Advil.8,9

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Runner with ankle pain

Musculoskeletal pain

Learn more about acute strains and sprains and how they can be relieved.

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