Fever in Adults
- Fever in Adults Overview
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Fever in Adults Overview
A fever is higher-than-normal body temperature. It is a symptom caused by a variety of illnesses.
Every one of us has experienced the wave of chills and exhaustion that a fever causes. Fever usually occurs in response to an infection or inflammation. However, many other causes are possible, including drugs, poisons, cancer, heat exposure, injuries or abnormalities to the brain, or disease of the endocrine (hormonal) 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 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 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 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.
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Fever (in Adults)
Allergy and Hay Fever Medications »
What are allergies?
An allergic reaction occurs when the immune system responds to a foreign substance in an abnormal fashion. The immune system normally protects the body from harmful agents like bacteria and toxins. The body's abnormal response to a harmless substance (called an allergen) is called a hypersensitivity, or an allergic reaction. Generally, these reactions are due to interactions between the allergen and the family of proteins, IgE, resulting in activation of cells in the body called mast cells and basophils.
What causes allergies?
Many substances in the environment can become allergens, but only in genetically susceptible persons. Dust mites, animal hair or danders, pollens, medications, foods, and insect venoms are examples of allergens. Approximately 20% of the US population is potentially allergic.
Reactions may be in the nose (hay fever), eyes (conjunctivitis), chest (asthma), or it can be systemic (anaphylaxis), me...
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Fever of Unknown Origin »
Fever of unknown origin (FUO) was defined in 1961 by Petersdorf and Beeson as the following: (1) a temperature greater than 38.3°C (101°F) on several occasions, (2) more than 3 weeks' duration of illness, and (3) failure to reach a diagnosis despite one week of inpatient investigation.
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