Temperature 101: How to Accurately Check Your Child’s Temperature

Evan has a fever. You can tell just by looking at him. But you wonder why his temperature varies so much depending on what type of thermometer you use. Which one is accurate? Surely the highest? When your child is sick, the last thing you want to do is rely on a method that gives unreliable readings. Or worse, incorrectly check his temperature.  

As parents, when our child is sick we want reliable answers fast. That means knowing the most precise way to check a child’s temperature and having the right tools to do it. The best way to check a child’s temperature varies based on age. Rectal temperatures are most accurate regardless of age. However, you will probably get plenty of pushback if you come to take your 14-year-old’s temperature with a rectal thermometer. To assist parents, we have devised a Temperature 101 Tip Sheet for the most precise temperature checking.

Digital is Best
While you probably grew up with a glass thermometer containing mercury, they are not considered safe. Today, most pharmacies offer mercury-free thermometers. However, these are not nearly as accurate as their digital counterparts.

Rectal Temperature Taking
For the most accurate reading, temperatures should be checked rectally if a child is younger than three years of age. To measure your child’s temperature rectally:

1. Clean thermometer with rubbing alcohol and rinse off. Apply a small amount of petroleum jelly onto the end of the thermometer.
2. Have child lay face down on a hard surface to restrict movement. Insert ½ to 1 inch of the thermometer into the rectum. Hold the thermometer loosely between fingers with the hand cupped over their bottom. Alternately, you can let the child lay on their back and lift their legs up to their chest while taking their temperature. Keep the thermometer in place for one minute or until it makes a beep sound indicating the reading is complete.
3. Always clean the thermometer with rubbing alcohol after use and label it, so it is not accidentally used orally.
4. The rectal temperature reading is accurate. There is no need to add or subtract a degree. Keep a log of their temperatures, times and if any medicine is given to provide to their pediatrician should seeing them become necessary.

Oral Temperature is More Accurate than Axillary
When deciding whether to check your child’s temperature orally (in the mouth) versus axillary (under the arm), oral temperature readings are more precise. To measure your child’s temperature orally:

1. Clean the thermometer with rubbing alcohol and rinse off.
2. Insert the thermometer into their mouth and under their tongue. It should be placed towards the back of the palate. Keep in place for one minute or until the thermometer makes a beep sound indicating the reading is complete.
3. The thermometer reading is accurate, and you do not need to add a degree to the result as you would if measuring temperature under the arm.
4. Clean thermometer with rubbing alcohol. Keep a log of temperatures with times listed as well as any medicine provided.

Tympanic (Ear) Temperatures
Checking your child’s temperature using an ear thermometer is usually accurate. However, the reading can be inaccurate if the thermometer is not inserted correctly or if there is a buildup of earwax in the ear canal. Tympanic temperatures are not recommended in children less than six months of age.

Temporal Artery Temperatures
Another way to check a child’s temperature is temporally. Perhaps you have seen a thermometer swiped across their forehead and on either side of their head? While fast, the results will vary, so multiple and accurate readings are required. You will also notice that one side is warmer than the other, so checking both temples is necessary. New research indicates that temporal artery temperatures may be reliable in children younger than three months of age when properly measured.

If your child has a temperature, it is essential to keep track of it. Write down the time, temperature and any medication given. If the child is younger than three months of age, contact their pediatrician if their rectal temperature reading is 100.4 F or higher. For children older than three months of age contact their pediatrician if he/she:

• Has a rectal, temporal or tympanic temperature reading of 100.4 F or higher.
• Has an oral temperature of 100 F (37.8 C) or higher
• Has an axillary (armpit) temperature of 99 F (37.2 C) or higher

The team at Rainbow Pediatrics is here to keep your family healthy. If you have any questions about how to accurately check your child’s temperature, give our office a call and schedule an appointment with one of our pediatric providers.