If your infant is 3 to 6 months old with a temperature above 102, call your pediatrician. Picture: Pixabay

Washington - Many parents panic when their child feels warm. But a fever is not a disease itself. It's just a symptom, or rather a sign that the body is trying to fight off an illness. 

The American Academy of Pediatrics defines a fever as a temperature of 100.4 degrees (about 38 degrees Celsius) or higher. 

Here are the fever facts all parents need to know.

What kind of thermometer is best?

Rectal thermometers are the most accurate and preferred method for taking a newborn baby's temperature. For older infants and toddlers, who probably won't hold still long enough for a rectal thermometer, a digital forehead thermometer, temporal artery thermometer or ear thermometer is fine. I have a few types in my home and at my office. 

For safety reasons, if you have an old mercury thermometer lying around, don't use it, as mercury spills from a broken thermometer can be dangerous. 

Should I really use a rectal thermometer?

Although the idea may seem uncomfortable to you, it won't hurt your baby. Just place your baby on his back, as you would to change a diaper. Unfasten the diaper and lift the legs up with one hand, as you would to wipe your baby's bottom. Coat the end of the thermometer with a clear lubricant and insert about half an inch into the rectum. Digital thermometers provide a quick, fairly accurate reading.

READ: Highest number of children with scarlet fever since 1982

When should I call the pediatrician?

If your baby is younger than 3 months and has a temperature of 100.4 degrees or higher, you should call your pediatrician right away (even if it's the middle of the night) because little ones can get very sick very quickly and should be evaluated as soon as possible.

If your infant is 3 to 6 months old with a temperature above 102, call your pediatrician. She probably will ask questions about your baby's symptoms to determine whether your baby should be evaluated right away or if you can wait and watch the baby at home.

For children older than 6 months, a temperature of 104 or higher warrants a call (although you'll probably be calling before you read this). Otherwise, they can usually be watched at home as long as they are alert, interactive and drinking fluids. If the symptoms haven't improved within two or three days or if they are worsening, see your pediatrician.

Always call your pediatrician if your child of any age has a fever along with any of the following symptoms: refusal or inability to drink fluids, seizure, continuous crying, irritability after bringing down the fever with appropriate medication, hard to wake up, confusion, rash, stiff neck, trouble breathing, persistent vomiting or diarrhea, or if the fever lasts more than three days.

What if I'm getting different readings?

Different thermometers will read slightly different temperatures, and don't be surprised if your ear thermometer gives you a different reading in each ear. Varying numbers are okay. As long as your child is older than 3 months, the precise number is not the main concern. What matters most is how your child is acting, eating and sleeping, and what other symptoms your child has (such as coughing or vomiting).

How can I get the most accurate reading possible?

Make sure you take off any hat, hoodie, turtleneck or swaddle for a few minutes before you take a forehead reading or you will get an elevated number. The thermometer is measuring the temperature of blood flowing through the temporal artery, so any bundling or extra clothing near the head can artificially elevate the reading. If a child is outside in cold air, and the skin feels cold to the touch, that also could affect the reading, making it artificially low. 

Wait five minutes after the child comes inside to get a more accurate temperature. And if you are taking a child's temperature orally right after he or she has had a hot or cold beverage, it could cause an incorrect reading. Again, wait five minutes before taking his temperature.