How to take your child’s temperature at any age

Your young child seems sick and appears flushed or hot. To tell if they have a fever, of course, you need to take their temperature. But, knowing the best way to do that can be confusing.

There are several kinds of thermometers out there, and places on the body to use them, so which one should you use, what temperature indicates a fever and what should you do if your child has one?

Cape Cod Hospital pediatric hospitalist Geoffrey C. Schreiner, MD says your child’s pediatrician can help prepare you for using thermometers and dealing with childhood fevers.

“I always tell them to bring their thermometer with them to an appointment,” he said.

Your child’s pediatrician or their staff can demonstrate how to properly take a temperature, check a digital thermometer’s calibration to ensure it’s working accurately and go over how to clean a thermometer, he said.

“People should not be using the mercury and glass ones. It’s safer to use the digital ones,” cautioned Dr. Schreiner, who is employed by Boston Children’s Hospital (BCH) and works at Cape Cod Hospital as part of a collaboration between Cape Cod Healthcare and BCH.

Age determines where on the child’s body their temperature should be taken, Dr. Schreiner said. Here is what he advises:

• Under 3 months, take it rectally.
• Above 6 months, a tympanic thermometer that inserts into the ear may be used.
• At 4 years old and up, oral temperature may be taken.

In addition:

• Digital thermometers may be used to take an axillary temperature from under the arm.
• At any age, a temporal or forehead infrared scan may be used.

According to the American Academy of Pediatrics (AAP), rectal and oral readings provide the most accurate temperatures. The AAP says children’s normal temperature ranges from 97 up to 100.4 degrees F (38 degrees C). A fever is any temperature of 100.4 degrees F or higher in any childhood age group, Dr. Schreiner said.

Instructions for Five Methods

The following descriptions of how to take a child’s temperature at each body part is from the AAP and the U.S. Food and Drug Administration.

Rectal: Clean the tip of thermometer with warm soap and water or rubbing alcohol, rinse and dry. Put a dab of petroleum jelly on the end and turn on thermometer. Hold child either face down with one hand across lower back or face up with knees drawn up and one hand against back of thighs. Use free hand to insert tip 0.5-1.0 inches into rectum. Leave in until thermometer beeps and check readout. Clean thermometer again.

Oral: Clean thermometer. Don’t take temperature within 15 minutes of when child last ate or drank. Put tip under child’s tongue toward rear of mouth. Keep in position till thermometer beeps and then check reading. Clean thermometer before storing.

Axillary: Put thermometer tip in child’s bare armpit. Wait for beep to read.

Temporal: Follow manufacturer’s directions, as devices vary somewhat. Child’s head should be clean and dry with no hair or clothing blocking skin. In general, turn on infrared thermometer and aim it perpendicular to child’s forehead at distance specified by manufacturer. If readout displays error signal, retake temperature.

Tympanic: Don’t use shortly after child has been swimming or bathing and avoid if child has an earache. Place a clean cover over the thermometer tip. Press the ear back slightly and Insert tip at right angle to head, pointed toward eye on far side of head. Turn on thermometer and wait for the beep.

What to Do if Your Child Has a Fever

Under 2 months old, immediately contact your pediatrician or go the local emergency department, Dr. Schreiner said. Further tests may be needed to determine what type of infection is causing the fever. These could include a urine sample or, if meningitis is suspected, a lumbar puncture.

In general, he said, children under age 2 need to see the pediatrician if a fever persists for a day or two. Over age 2, do the same if the fever last two to three days. Be sure to document any symptoms – such as your child being fussy, vomiting, having diarrhea, stuffy nose, cough, trouble breathing, a headache or stiff neck. Parents should also consider other factors beyond illness, such as was the child at the beach all day?

“There can be other reasons a child’s temperature could be high,” Dr. Schreiner said.

Parents can try over-the-counter children’s medications to lower fever. Children’s versions of acetaminophen (Tylenol) can be given. Ibuprofen (Advil, Motrin) can only be used in children older than 6 months, Dr. Schreiner said. For either medicine, it’s important to know your child’s weight to give the correct dose. Be sure to note the amount given, and when, so this information can be relayed to the pediatrician.

Many health organizations say aspirin (salicylate) shouldn’t be given to treat viral fevers in children and teens – or at all, in most cases, for those under 19. According to the National Institute of Neurological Disorders and Stroke, this medicine has been associated with developing Reye’s (or Reye) syndrome, a rare and potentially fatal disease affecting the liver and brain.