Fever usually supports the work of the immune system in the fight against pathogens. The increased heat sets metabolic processes in motion that can help with disease prevention. Therefore, fever occurs in almost all infections and inflammations.
Slightly elevated temperatures over one to two days are generally considered harmless. However, if the temperature increases to over 39 degrees Celsius or does not decrease after two days at the latest, you should consult a doctor - especially if additional symptoms are added. The condition is, however, that the body is not already weakened by other diseases. Measuring the fever is an important criterion for the course of the disease. But which method and device are suitable?
Measuring methods at a glance
- Electronic clinical thermometers are easy to read, measure quickly and do not cost much, but they require a battery.
- Since the most significant fever temperature can in principle be measured only inside the body - which corresponds to the so-called core temperature - the rectal fever measurement is the most accurate method. It is also applicable to children and restless patients if they are not left alone during the measurement. The rectal measured temperatures are about 0.4 degrees Celsius higher than those in the mouth or under the armpit.
- The sublingual measurement (under the tongue) is also common. The thermometer is placed 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 warm drinks and food should be taken beforehand. The method is unsuitable for nasal congestion and coughing, confused people and infants as they bite on the thermometer.
- Temperature measurement in the armpit requires a long measurement time of up to eight minutes. This also applies to the temperature determination in the groin.
- Glass thermometers offer a good alternative in the digital age with regard to their measuring 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 well as the poisonous mercury. The disadvantage: glass fiber thermometers are indeed very 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 pretty much the temperature inside the body. With measuring times in the lower second range, the devices are very fast. The prerequisite for this, however, is that the probe tip is precisely placed, which works best when the ear canal is stretched by pulling gently on the ear.
- Sensor thermometers determine the temperature when rolling over the skin surface relatively quickly and hygienically. The forehead and temple area are considered as good measuring locations for the infrared measurement, but so far there is still a lack of reliable data.
- Comfortable for children up to two years are the pacifier thermometers. Just like frontal and patch thermometers, the pacifier thermometers do not work very well and are therefore not recommended. However, the readings at least provide a decision support for the parents, whether a visit to the doctor is indicated.
Fever measurement: what to consider?
Throughout the day body temperature fluctuates due to different metabolic activities. It is lowest in the early morning, highest in the late afternoon and early evening. In women, one to two days after ovulation, the body temperature increases by half a degree Celsius.
All these are factors that should be taken into account when it comes to fever measurement, as the transitions between the individual fever areas are in tenths of a degree increments. For example, a measured value of 39.0 degrees is still considered to be a moderate fever, 39.1 is already considered to be high. This shows that temperature gradients are more important than individual measured values.