Fever generally supports the work of the immune system in the fight against pathogens. The increased heat sets metabolic processes in motion, which can help in the defense against disease. That is why fever occurs in almost all infections and inflammations. But how can you measure a fever correctly? Where should you take a temperature and what types of clinical thermometers are available? You can find out here.
Measuring a fever correctly
Slightly elevated temperatures over one to two days are generally considered harmless. However, if the temperature rises above 39 degrees Celsius or does not drop after two days at the latest, you should see a doctor – especially if other signs of illness are added. The prerequisite, however, is that the body is not already weakened by other illnesses. It is important to measure the fever regularly in order to be able to correctly assess the course of the illness. But which method and which device are suitable? In the following, we will introduce you to different methods for taking a fever.
Measuring methods at a glance
Here you will find various methods and devices for taking a temperature. When choosing, it is important to weigh the advantages and disadvantages:
- Electronic clinical thermometers are easy to read, measure quickly and do not cost much, but they require a battery.
- Glass thermometers also offer a good alternative in the digital age in terms of their measurement accuracy. Today, there are glass thermometers with a non-toxic metal mixture. Such measuring liquids are mixed together from gallium, indium and tin and work just as accurately as the toxic mercury, which was previously used in clinical thermometers. The disadvantage: glass clinical thermometers are particularly hygienic and easy to clean, but not unbreakable.
- Ear thermometers measure the temperature via the infrared radiation emitted in the ear canal. The radiation represents thereby quite accurately the temperature inside the body. With measurement times in the lower second range, the devices are very fast. However, a prerequisite for this is that the probe tip is placed accurately, which is best achieved when the ear canal is stretched by gently pulling the ear.
- Sensor thermometers (for example, forehead thermometer) determine the temperature relatively quickly and hygienically when rolling over the skin surface. Forehead and temple area are considered good measurement locations for infrared measurement, the data are not always reliable, as it is comparatively easy to measurement errors.
- Convenient for children up to two years are the pacifier thermometers. Just like forehead and patch thermometers, however, the pacifier thermometers do not work very accurately and are therefore not recommended. However, the readings at least provide a decision aid for parents whether a visit to the doctor is indicated.
Where should you take a temperature?
Especially parents of children, but also adults often wonder where it is best to take a temperature: in the mouth, under the armpit or rectally? Here’s what you should know:
- Since the most informative fever temperature can in principle only be measured inside the body – which corresponds to the so-called core temperature – rectal fever measurement is considered the most accurate method. It can also be used with children and agitated patients if they are not left alone during the measurement. The temperatures measured rectally are about 0.4 degrees Celsius higher than those in the mouth or under the armpit.
- Common is also the sublingual measurement (under the tongue). The thermometer is placed for this as far back in the mouth as possible under the left or right side of the tongue. The mouth should be closed and no cold or hot drinks or food should have been taken beforehand. Unsuitable is the method in case of nasal congestion and cough, confused people and small children, because they bite on the thermometer.
- Temperature measurement in the armpit requires a long measurement time up to eight minutes. This also applies to the temperature measurement in the groin.
Fever measurement: what to consider?
During the day, the body temperature fluctuates due to different metabolic activities. It is lowest in the early morning hours and highest in the late afternoon and early evening. In women, body temperature also increases by half a degree Celsius one to two days after ovulation.These are all factors that should be taken into account when measuring fever, since the transitions between the individual fever ranges occur in tenths of a degree increments. For example, a reading of 39.0 degrees is still considered a moderate fever, while 39.1 is already considered a high fever: this shows that temperature gradients are more important than individual readings.
