By Maren Dunn, D.O. ExploreBigSky.com Health Writer

What happens to cause a fever? How do fever-reducing medicines help?

– Michael, Bozeman

It’s influenza season, a time when fever becomes rampant in our community. Fever, defined as the elevation of an individual’s core body temperature beyond the normal daily range, can be one of the most unpleasant symptoms of illness. Typically it is due to infection.

The brain has a thermostat that works similar to the one in our homes. It’s called the hypothalamus. Here, the set point for your body temperature is determined. When fighting infection, the body produces chemicals that trigger the hypothalamus to increase the temperature set point to a higher level.

When the blood surrounding the hypothalamic nerves is a lower temperature than the set point, the body is stimulated to produce heat. First, blood vessel constriction in the extremities reduces heat loss from the skin. This can make the hands and feet cold while the core body temperature rises. In some cases the muscles twitch, or shiver, producing more heat. This is when a person feels cold or “chilled” and wraps up in a blanket and clothing layers. Essentially, your brain makes you feel cold while our body works to increase its temperature to a new set point.

When the infection is gone or fever-reducing medicine like acetaminophen, aspirin or ibuprofen are taken, the set point returns to normal. Often the person will feel hot and will likely sweat, which helps reduce their body temperature back to the normal setting. Sometimes a cool bath or cool compresses are used to reduce body temperature. However, these methods should only be used together with fever-reducing medicine since a cool bath alone will not reset the hypothalamus.

Studies show that treating fever does no harm, nor does it slow the healing of an illness. In fact, medicines such as acetaminophen and ibuprofen, which can be used together, reduce fever and also allay other symptoms including headaches and joint and muscle pain. It’s important to remember children under 16 should not take aspirin. If a person cannot tolerate medicine by mouth rectal suppositories are effective. See your medical provider if your fever does not reduce with medicine or if it is coupled with worrisome symptoms such as shortness of breath, dizziness, abdominal pain or severe vomiting.