Beyond specifically following the instructions on your thermometer, here is advice from doctors on getting accurate readings about possible fever:

• Use a digital thermometer: Medical associations no longer recommend glass thermometers filled with mercury, an environmental toxin. If you have an older thermometer, contact your local health department about disposing of it safely.

• Time it right: Don't check for fever soon after eating something hot or cold. Hot baths, layers of warm clothing and vigorous exercise also can throw off readings.

• Tips for oral readings: Keep the thermometer under your tongue toward the back of your mouth. Use your lips to close your mouth around it — but don't bite down on it. Breathe through your nose, and don't open your mouth to talk.

• Rectal readings: Place the child on her stomach on your lap or a flat surface such as a diaper changing table. Rub a little petroleum jelly on the tip of a rectal thermometer and insert it ½ to 1 inch inside the rectum (never push if you meet resistance).

• Ear readings: If a thermometer comes with plastic covers, dispose them after a single use. Gently place the thermometer into the entrance of the ear canal; do not push.

• Underarm readings: Make sure the child's armpit is dry and take off his shirt so only skin will touch the thermometer.

• Recognize other signs of fever: Those include flushed cheeks, chills, muscle pain and headaches. Also note that body temperature tends to be higher at night than in the morning.

• Don't just look at fever: When considering how sick someone is, note changes in eating and sleeping habits, alertness and mood. All can help you decide if you need a doctor.