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How do I take my baby’s temperature?

If you're concerned about a fever in your baby, how you take their temperature is somewhat dependent on the age. Under the first two months, it's most important to get an accurate temperature. What I usually recommend is to take it under the arm first, and if it's higher than 99.5 then take it rectally, because rectal is the most accurate temperature. To take it rectally, some people are a little concerned that that might hurt their baby, but it won't. If you put it in about a centimeter into the rectum and take it and it's over 100.5, that's when it's concerning, and your pediatrician will want to know about that.

After the age of 2 months, it's not as important how you take the temperature. You can take it under the arm and get an idea of how high the temperature is.

Always use a digital thermometer when taking a baby’s temperature. Two ways to measure the temperature are under the arm (called the axillary method) and rectally. Start with the axillary method: Place the thermometer under the arm, and hold the arm in place. To measure a rectal temperature, wash your hands and the thermometer. Dab a little petroleum jelly on the thermometer’s end, and press the “on” button. Lay the baby on his or her back on a firm surface, lift his or her legs, and gently spread the cheeks. Use both hands, one for the thermometer and the other to hold your baby securely. Gently insert the tip about one-half inch into the baby’s rectum. Hold it in place until it beeps, then slowly withdraw and read it. With either method, notify your pediatrician of a temperature over 100.3 degrees Fahrenheit, and say which method you used.
Dr. Jeanne Morrison, PhD
Family Practitioner

The best ways to take a temperature in a newborn are rectal and axillary. Because babies may have fluid in their ears, wait until the baby is over three months of age before using an ear thermometer. Oral temperatures are usually not use in children until they are 4-5 years old and able to follow directions and be cooperative.

A rectal temperature us the most accurate measure of the newborn’s core or body temperature. Using a clean, digital thermometer, coat the end with a small amount of water soluble lubricant. Place the baby across your lap or on the changing table with the legs in the air. Turn on the thermometer and slowly insert it into the rectum, no further than ½ inch. Hold the thermometer in place to prevent injury. When it beeps, remove it and note the temperature. Clean the thermometer with alcohol before putting it away.

An axillary temperature is easier to take, but not as accurate as a rectal temperature. To take an axillary temperature remove the baby’s shirt and make sure the underarm area is dry. Hold or position the baby securely and place the tip of the thermometer into the pit of the axilla. Hold the baby’s arm snuggly to the side of the body to stabilize the thermometer. When the thermometer beeps, remove it and note the temperature. Clean the thermometer before putting it away.

Always use a digital thermometer. Glass thermometers can break and cause injury to the baby.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.