Measure fever correctly: Here's how

Mouth, armpit, bottom - where is the best place to measure a fever? And which thermometer is the most accurate? What you should know

Text in simple language

To get straight to the point: if you want an exact result, you should measure your fever rectally, i.e. in your buttocks. This method has the lowest measurement inaccuracy. Especially when patients are already feverish, the results of other thermometers sometimes differ greatly from the actual temperature. Determining a normal body temperature is not easy. Because there can be significant fluctuations in the course of the day and also individually. Usually the temperature is somewhere between 36.5 and 37.5 degrees rectally. When we do physical activity, for example, we heat ourselves up and the temperature in the evening is generally a little higher than in the morning.

What is the best thermometer to measure with?

The old glass thermometer is likely to have had its day in most households. There is also the digital thermometer among the so-called contact thermometers. Infrared measuring devices determine the temperature either in the ear or on the forehead.

  • Digital thermometer (also electronic contact thermometer): The temperature can be read digitally. These models are very reliable, especially when, as mentioned at the beginning, they are used rectally. If that is not possible, a measurement under the tongue is also relatively accurate.
  • Ear thermometer: It measures the eardrum in seconds using infrared rays. However, the thermometer is not suitable for an otitis media. If children find the rectal measurement uncomfortable, an ear thermometer is a good alternative. Ask at the pharmacy about a device that is suitable for the age of the child.
  • Forehead thermometer: Here, too, infrared rays measure the temperature, but on the forehead. However, this can also lead to incorrect measurements.

Explanatory video: taking a fever

What do I have to consider when taking measurements in the buttocks, mouth and armpits?

The rectal method, while not particularly popular, is very accurate. To do this, grease the thermometer tip with a suitable cream beforehand. The pharmacist can advise you on this. To measure, you should lie on your side or on your back.

If you want to measure a fever in your mouth, there are a few things to keep in mind. Do not eat or drink anything warm or cold about 30 minutes beforehand. Place the tip of the thermometer under your tongue and keep your lips closed while taking the measurement. This method is therefore not suitable for people with a cold or breathing problems through the nose. The measurement in the mouth is - if carried out correctly - relatively reliable.

When measuring under the armpit, deviations of up to two degrees can occur. Make sure that the forearm is close to the side of the body.

How do I use ear and forehead thermometers correctly?

Read the instructions for use of the respective device. To measure, you have to pull your ear back upwards slightly so that the ear canal becomes free. In the case of infants, on the other hand, only pull backwards. Important: The child should not lie on the respective ear beforehand. That falsifies the result. The temperature of the eardrum is about 0.3 to 0.5 degrees lower than that measured rectally.

With the forehead thermometer you can measure the temperature on the temple. This is more convenient than other methods, but relatively imprecise. The advantage: you can also measure the child's temperature while they are sleeping.