How to Measure Fever with Different Thermometers

Learn about the five types of thermometers that can take your child's temperature, plus the ways to treat fever at home.

Fever is a common occurrence in children; it indicates that the body is trying to fight off some kind of cold or infection. If your child has a fever, he may be warm to the touch, flushed, or sweating, or have chills. Because being bundled in too many clothes or blankets may result in fever-like symptoms, taking your child's temperature is the best and most reliable way to determine whether a fever is present.

Knowing how to use a thermometer to measure your child's temperature is important. Temperatures can be taken in several different places on the body with various thermometers; whichever type of thermometer you use, be sure to read the directions carefully. Almost all thermometers require correct positioning to get the most accurate reading. Although many fevers run their course without medical intervention, be sure to see your doctor if your child's temperature is higher than 102° for more than 24 hours or if the fever is higher than 104°. For infants under 3 months, call the doctor if the fever is over 100.4°.

    Types of Thermometers

    For a child over 3 months old, you can choose from five different types:

      1. Digital Temple Thermometers are fast, fairly accurate, and good to use when your baby is too young to sit still. Make sure that the sensor is near the temporal artery (between the outside edge of the eye and the hairline). Look at the directions carefully to make sure you get an accurate reading.
      2. Digital Ear Thermometers are quick and accurate. Pull on the ear a little to position the thermometer properly. These are a great option for squirmy little ones because they are so fast, but the end needs to be inserted correctly for an accurate reading.
      3. Digital Oral Thermometers offer fast and accurate readings. These require more time to read than other thermometers do, and they are better for children who are able to sit still and close their mouths for 30 seconds. Most oral thermometers can also be used as underarm thermometers; this is a noninvasive way to measure a fever, but be aware that the temperature under the arm is lower than the temperature at the core of the body.
      4. Wearable Thermometers can be used continuously and do not require waking or disturbing the child. Their ability to track the fever across time can be helpful.
      5. Forehead Thermometer Strips are not as accurate as thermometers, but they are the least invasive and disruptive way to take a child's temperature. Simply hold the strip on the forehead until the color registers along the strip.

        Taking Temperatures with a Rectal Thermometer

        For children younger than 3 months, rectal thermometers provide the most accurate readings, but they can also be used for children older than 3 months. Taking a temperature with a rectal thermometer is quick and easy. Follow these steps:

          1. Make sure that the thermometer tip is clean. Wash it with soapy water or alcohol and dry it.
          2. Put a little petroleum jelly on the thermometer tip. This makes it easier to insert.
          3. Put your baby face up on the changing table.
          4. Lift your baby's legs (knees to chest) as though you were changing a diaper.
          5. Spread your baby's buttock cheeks apart and insert the thermometer into the rectum.
          6. Insert the thermometer only a half-inch to an inch. Stop inserting the thermometer if there is any resistance. Pushing the thermometer too far in could hurt your baby's rectum.
          7. Hold your baby still. Use one hand to keep him still while using the other to hold the thermometer. Keep your baby from squirming as much as possible so that the thermometer does not slide further in or out.
          8. Read the thermometer. It may take up to two minutes for the thermometer to register a reading, but when the thermometer beeps, remove it carefully.
          9. Clean the thermometer again and store it.

            Although many fevers run their course without medical intervention, call your doctor right away if your baby is under 3 months and has a rectal thermometer reading of over 101.4°. For little ones between 3 to 6 months, any temperature above 101° warrants a call to the doctor. Regardless of age, call the doctor immediately if your baby has a fever over 104°.

              Treatment for Fever

              Although there is no specific way to prevent a fever, keeping your child healthy is essential. Fruits and vegetables can boost immune systems and fight infection, and proper hand-washing can reduce the risk of sickness. The following steps are some easy ways to treat a fever.

                • Give your child acetaminophen (Children's Tylenol) or ibuprofen (Children's Advil).
                • Give a lukewarm bath (for low-grade fevers).
                • Put the child in light clothing and use only one blanket.
                • Serve Popsicles and cold foods for comfort.
                • Have your child drink plenty of water and clear liquids.

                  Never give your child aspirin to treat a fever because it can cause a rare but serious disease called Reye's syndrome.

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