Aches, Pain, Fever (cont.)

Medical Author:
Medical Editor:

What causes a fever?

Reader Stories

Fever is the result of an immune response by your body to a foreign invader. These foreign invaders include viruses, bacteria, fungi, drugs, or other toxins.

These foreign invaders are considered fever-producing substances (called pyrogens), which trigger the body's immune response. Pyrogens tell the hypothalamus to increase the temperature set point in order to help the body fight off the infection.

Fever is a common symptom of most infections, and thus a risk factor for fever is exposure to infectious agents. In children, immunizations (such as flu shots) or teething in may cause low-grade fever. Autoimmune disorders, medication reactions, seizures, or cancers may also cause fevers.

What are the signs and symptoms of a fever?

A fever can cause someone to feel very uncomfortable. Signs and symptoms of a fever include the following:

  • Temperature greater than 100.4 F (38 C) in adults and children
  • Shivering, shaking, chills
  • Aching muscles and joints or other body aches
  • Headache
  • Intermittent sweats or excessive sweating
  • Rapid heart rate and/or palpitations
  • Skin flushing
  • Feeling faint, dizzy, or lightheaded
  • Weakness
  • With very high temperature (> 104 F/40 C), convulsions, hallucination, or confusion is possible. Seek medical attention.

How is a fever diagnosed?

Along with having the generalized symptoms of a fever, taking one's temperature with a thermometer can confirm the diagnosis of a fever. A temperature greater than 100.4 F in adults or children is considered a fever.

Medically Reviewed by a Doctor on 6/12/2015

Patient Comments

Viewers share their comments

Fever - Treatments Question: What treatments helped to reduce your fever?
Fever - Signs and Symptoms Question: What signs and symptoms did you or your child experience along with a fever?
Fever - Complications Question: Did you or your child experience any complications when you had fever? If so, what were they?
Fever - Cause Question: What caused your fever?