The hypothalamus knows what temperature your body should be (usually around 98.6°F/37°C) and will send messages to your body to keep it that way.

Sometimes, though, the hypothalamus will "reset" the body to a higher temperature in response to an infection, illness, or some other cause. Why? Researchers believe that turning up the heat is a way for the body to fight the germs that cause infections, making it a less comfortable place for them. It's important to remember that fever by itself is not an illness — it's usually a sign or symptom of another problem.

Causes

• Infection: Most fevers are caused by infection or other illnesses. A fever helps the body fight infections by stimulating natural defense mechanisms.
• Overdressing: Infants, especially newborns, may get fevers if they're over-bundled or in a hot environment because they don't regulate their body temperature as well as older kids. But because fevers in newborns can indicate a serious infection, even infants who are overdressed must be checked by a doctor if they have a fever.
• Immunisations: Babies and kids sometimes get a low-grade fever after getting vaccinated.

How do I take the temperature?

For babies between 3 months and 6 months old, a digital rectal thermometer is the best choice, but a temporal artery thermometer can also be used.

Steps

• Wash the end of the thermometer with soap and water and rinse with water.
• Moisten the tip of the thermometer with a lubricant, such as petroleum jelly.
• Then, place your child: belly-down across your lap or on a firm, flat surface and keep your palm along the lower back or face-up with legs bent toward the chest with your hand against the back of the thighs.
• With your other hand: Insert the lubricated thermometer into the anal opening about ½ inch to 1 inch (about 1.25 to 2.5 centimeters), or until the tip of the thermometer is fully in the rectum. Stop if you feel any resistance.
• Steady the thermometer between your second and third fingers as you cup your hand against your child's bottom. Soothe your child and speak quietly as you hold the thermometer in place.
• Wait until you hear the appropriate number of beeps or a signal that the temperature is ready to be read. Write down the number on the screen, noting the time of day that you took the reading.

It's a fever when a child's temperature is at or above one of these levels: measured rectally (in the bottom): 100.4°F (38°C)But how high a fever is doesn't tell you much about how sick your child is. A simple cold or other viral infection can sometimes cause rather high fever (in the 102°–104°F/38.9°–40°C range), but this doesn't usually mean there's a serious problem. In fact, a serious infection, especially in infants, might cause no fever or even a low body temperature (below 97°F or 36.1°C).Because fevers can rise and fall, a child might have chills as the body's temperature begins to rise. The child may sweat to release extra heat as the temperature starts to drop.

Sometimes, kids with a fever breathe faster than usual and may have a faster heart rate. Call the doctor if your child has trouble breathing, is breathing faster than normal, or is still breathing fast after the fever comes down.

Remedies

• Feed your baby frequently to prevent dehydration.
• Dress your child in lightweight clothing and cover with a light sheet or blanket. Overdressing and over bundling can prevent body heat from escaping and can cause the temperature to rise.
• Make sure your child's bedroom is at a comfortable temperature — not too hot nor too cold.
• While some parents use lukewarm sponge baths to lower fever, this method only helps temporarily, if at all. In fact, sponge baths can make kids uncomfortable. Never use rubbing alcohol (it can cause poisoning when absorbed through the skin) or ice packs/cold baths (they can cause chills that can raise body temperature).