Aches, Pain, Fever (cont.)

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What causes a fever?

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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 shots) or teething in may cause low-grade fever. Autoimmune disorders, medication reactions, seizures, or cancers may also cause fevers.

Fever itself is not contagious; however, if the fever is caused by a viral or bacterial infection, the infection may be contagious.

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, and chills
  • Aching muscles and joints or other body aches
  • Headache
  • Intermittent sweats or excessive sweating
  • Rapid heart rate and/or palpitations
  • Skin flushing or hot skin
  • Feeling faint, dizzy, or lightheaded
  • Eye pain or sore eyes
  • Weakness
  • With very high temperature (> 104 F/40 C), convulsions, hallucinations, 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.

Different tests may be done by a doctor, such a blood and imaging tests, to determine the cause of a fever and if the cause of the fever needs to be treated.

Medically Reviewed by a Doctor on 10/21/2015

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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?
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