Do you remember the last time you got sick? It may have started out as an upset stomach or a sore throat with a cough. Eventually, though, you may have started to feel very tired and extremely warm. Placing your hand on your forehead revealed what you suspected: a sweaty forehead that felt much warmer than normal.

What are we talking about? A fever, of course! A fever is a sure sign that your body is fighting something and likely needs some medicine.

Human beings have a normal body temperature of about 98.6º F. Some people may have a normal body temperature slightly above or below this mark. Your temperature may also vary naturally throughout the day, running a little cooler in the morning and a little warmer in the evening. For the most part, though, an upward departure from 98.6º F means you have a fever.

The body's temperature is regulated by a part of the brain called the hypothalamus. Located in the center of the brain, the hypothalamus is like the body's thermostat. It keeps track of changes to your body temperature and sends messages to the different parts of the body to keep it at the proper temperature.

So how do fevers occur? They're most often caused by the invasion of germs, such as bacteria and viruses. Germs can cause certain chemicals to enter your bloodstream, making you feel ill. When the hypothalamus detects these chemicals in your blood, it communicates with the rest of your body to set your internal thermostat higher.

For example, rather than the normal 98.6º F, your hypothalamus might tell your body to raise its temperature to 102º F. Although it's no fun to have a fever, raising your body's temperature helps to fight the germs making you sick by making your body a less comfortable place for them to be. A fever also lets you know you have an infection that needs to be treated.

When you get a fever, you often shiver a bit at first. Shivering is actually one of the ways your body uses to create more heat to get your body temperature to the new, higher setting directed by the hypothalamus. Once your body gets to its new temperature, you'll feel plenty warm.

As soon as your body is able to fight the germs off, usually with the help of some medicine, your hypothalamus will reset your body's thermostat back to 98.6º F. You will likely begin to sweat more as your body uses the process of perspiration to help cool you down to the correct temperature.

Most fevers resolve themselves on their own. However, fevers in very young infants can be particularly dangerous. In addition, extremely high fevers of 104º F or higher in children might also necessitate contacting a doctor.

For most regular fevers, over-the-counter medicines like acetaminophen and ibuprofen will help fight a fever. If you have a fever, you'll also want to drink lots of fluids. As your body heats up with a fever, it can easily become dehydrated, so be sure to include plenty of fluids along with some extra rest.

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