What does your fever mean?

Body aches, chills, flushed skin and excessive sweating. If you’ve got these symptoms, your body might be battling an illness or infection. If you check your temperature and the thermometer reads 100.4 degrees Fahrenheit (38 C) or above – by medical definition, you are experiencing a fever.

“Fever is your body’s defensive response to pathogens from the outside,” says Dr. Rebecca Krasaeath, a family practice physician for Advocate Medical Group in Chicago, Ill. “This elevated temperature is actually beneficial to fighting viruses and bacteria.”

A fever is most commonly caused by infection. When your immune system feels attacked by an intruder, such as a virus or bacteria, it releases cytokines. This then causes an increase in your body’s hypothalamic set point, which acts as your body’s thermostat. When the thermostat is turned up, your body temperature rises, producing a fever.

However, be aware that different people have different body temperatures. What could be normal for you may be a concern for someone else. It is also a myth that people should have a constant temperature of 98.6 F. Body temperatures vary throughout the day. If your body temperature elevates slightly at some point, you could be experiencing hyperthermia.

“There is a distinction between fever and hyperthermia, which is when your body’s temperature goes up without a change in the hypothalamic set point,” says Krasaeath. “It’s easy to just refer to all elevated temperature as fever, but it’s important to understand that people’s temperatures fluctuate throughout the day.”

There are many non-harmful causes for elevated temperatures. These can include general daily variation, chewing gum, after meal effects, exercise and ovulation in women. Most people move about their day and never notice these changes in their body.

However, there are some harmful causes of fever. If you experience a fever that is accompanied by symptoms such as severe headaches, vomiting, chest pain, abdominal pain, mental confusion or seizures, this could be a sign of a serious illness. If you develop a high temperature, be careful to monitor your symptoms and contact a doctor if the fever and symptoms persist for several days with no improvement.

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