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How to tell when an adult is suffering from fever.

How to tell when an adult is suffering from fever.

How to Tell When a Fever in Adults Is Serious.

A fever (also termed pyrexia) is a higher-than-normal body temperature. It is a symptom caused by a wide variety of illnesses. Fevers may occur in anyone at any age; however, this article is specifically addressing fever in adults.

Every one of us has experienced the wave of chills and exhaustion that a fever causes. Fever usually occurs in response to an infection as with the flu, viruses that causes a cold, strep throat bacterial infection, or most infectious diseases, or with inflammation that occurs with tissue injury or disease (such as with some cancers). However, many other causes of fever are possible, including drugs, poisons, heat exposure, injuries or abnormalities to the brain, or disease of the endocrine (hormonal or glandular) system.

A fever rarely comes without other symptoms. It is often accompanied by specific complaints, which may help to identify the illness causing the fever. This can help the doctor determine which treatment is necessary.

  • Normal body temperature can vary depending on the individual, the time of day, and even the weather. For most people, a temperature of 98.6 F (Fahrenheit) (37 C or Celsius) is baseline.
  • Temperature is usually controlled by the part of the brain called the hypothalamus. The hypothalamus is like a thermostat for the body. It maintains normal temperature through heating mechanisms, such as shivering and increased metabolism, and cooling mechanisms, such as sweating and dilating (opening) blood vessels close to the skin.
  • Fever occurs when the body's immune response is triggered by pyrogens (fever-producing substances). Pyrogens usually come from a source outside the body and, in turn, stimulate the production of additional pyrogens inside the body. Pyrogens tell the hypothalamus to increase the temperature set point. In response, our body begins to shiver; our blood vessels constrict (close); we get under the covers in an attempt to reach the new temperature that is higher than our baseline. However, other pyrogens can be produced by the body, usually in response to inflammation; these are referred to as cytokines (also termed endogenous pyrogens).
    • Pyrogens (fever-producing substances) that come from outside the body include the following:
      • Viruses
      • Bacteria
      • Fungi
      • Drugs
      • Toxins

Body temperature measurements are usually measured by temperature devices inserted on or into the rectum, mouth, axilla (under the armpit), skin, or ear (ear thermometers). Some devices (laryngoscopes, bronchoscopes, rectal probes) may have temperature-sensing probes that can record temperature continually. The most common way to measure body temperature was (and still is in many countries) with a mercury thermometer; because of glass breakage and the possibility of subsequent mercury contamination, many developed countries use digital thermometers with disposable probe covers to measure temperature from all of the body sites listed above. Disposable temperature-sensitive strips that measure skin temperature are also used. Oral temperatures are most commonly measured in adults, but rectal temperatures are the most accurate because environmental factors that increase or decrease temperature measurements have the least effect on the rectal area. Rectal temperatures, when compared to oral temperatures taken at the same time, are about 1.8 F (0.6 C) higher. Consequently, an accurate measurement of body temperature (best is rectal core temperature) of 100.4 F (38 C) or above is considered to be a "fever" and the person has a febrile illness.

A newer option includes a temperature-sensitive infrared device that measures the temperature in the skin by simply rubbing the sensor on the body. These devices can be purchased in most pharmacies.

SOURCE: eMedicine-Health

When is a fever serious?

Call your doctor immediately if you have a high grade fever — when your temperature is 103°F (39.4°C) or higher. Get medical help if you have any kind of fever for more than three days. Let your doctor know if your symptoms get worse or if you have any new symptoms.


A fever may be a sign of serious illness if you have:

  • a severe headache
  • dizziness
  • sensitivity to bright light
  • stiff neck or neck pain
  • skin rash
  • difficulty breathing
  • frequent vomiting
  • dehydration
  • stomach pain
  • muscle cramps
  • confusion
  • seizures

Other signs that a fever may be serious are:

  • pain when urinating
  • not urinating enough
  • passing dark urine
  • passing urine that smells bad

Causes of serious fevers

If you have serious fever symptoms, let your doctor know if you have recently traveled to a different country or attended an event that had lot of people. This may help your doctor find out the cause.

Common causes of a fever in adults are:

  • viral infection (like the flu or a cold)
  • bacterial infection
  • fungal infection
  • food poisoning
  • heat exhaustion
  • serious sunburn
  • inflammation (from conditions like rheumatoid arthritis)
  • a tumor
  • blood clots

Some adults may have a higher risk of getting a fever. If you have a chronic health condition or have been treated for a severe illness, you may be more likely to get a serious fever.

Let your doctor know about any fever symptoms if you have:

  • asthma
  • rheumatoid arthritis
  • diabetes
  • Crohn’s disease
  • heart disease
  • sickle cell disease
  • liver disease
  • kidney disease
  • chronic lung disease
  • cystic fibrosis
  • cerebral palsy
  • stroke
  • multiple sclerosis
  • muscular dystrophy
  • HIV or AIDS

Some medications and treatments can also lead to a serious fever, these include:

  • antibiotics
  • blood pressure drugs
  • seizure medications
  • DTaP vaccine
  • pneumococcal vaccine
  • steroids
  • chemotherapy
  • radiation treatment
  • methotrexate
  • azathioprine
  • cyclophosphamide
  • post-transplant medications



A fever is not normally harmful on its own. Most fevers go away within a few hours to days as your body defeats an infection.

Help yourself feel better with these at-home flu remedies:

  • stay hydrated by drinking plenty of fluids, such as:
    • water
    • juice
    • soup
    • broth
  • eat light foods that are easy on the stomach
  • rest
  • use a cool compress, like a damp towel
  • take a warm sponge bath
  • dress in light, comfortable clothing
  • turn down the temperature in your room

Over-the-counter medications can help ease your fever and symptoms, like headaches and muscle pain:

  • ibuprofen (Advil, Motrin)
  • acetaminophen (Tylenol)
  • naproxen (Aleve, Naprosyn)

You may need treatment from your doctor for more serious causes of a fever. The treatment depends on the cause. Your doctor may prescribe medications to treat serious infections:

  • antibiotics
  • antivirals
  • antifungals

A fever may be a sign of serious illness. A high fever can also cause serious side effects.



Get emergency medical attention by going to the ER or calling an ambulance if you have any of these symptoms:

  • seizure or convulsions
  • fainting or loss of consciousness
  • confusion
  • hallucinations
  • severe headache pain
  • stiff or painful neck
  • difficulty breathing
  • hives or a rash
  • swelling in any part of the body

The bottom line

A fever in adults is usually not harmful on its own. It is a sign that your body is dealing with an infection or other illness. In some cases a high or long-lasting fever can be a sign of a serious illness. You may need urgent medical treatment.

Do not ignore a fever. Get plenty of rest and fluids to help your body heal. See your doctor if you have a fever that lasts longer than 3 days or if you have other severe symptoms.

If you have a chronic condition or have been treated for a serious illness, let your doctor know if you have any kind of fever.



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