Fever: Measure it well

Under the armpit, with the classic thermometers, or on the front with those with liquid crystals? Here are all the methods to correctly measure fever and interpret temperature data.

Fever is one of the mechanisms that our body performs to accelerate the reactions that lead to the destruction of viruses and bacteria.

If the high temperatures are detrimental to microbes, it is also true that they make life difficult for the cells causing a state of discomfort. In fact, in man, the temperature is programmed to vary in the range between 36.5°C and 37.5°C.

There is fever and fever

Since the fever is intended to create unfavorable conditions for the life of viruses and bacteria, if it does not cause excessive discomfort it is not appropriate to counteract it during an infectious disease, especially when it does not exceed 38°C.

Precisely for this reason, up to these temperature levels we talk about fever, while we define mild fever when the temperature fluctuates between 38.1°C and 38.5°C. While it is moderate when the level does not exceed 39°C and high when it touches 39.5°C.

Above this temperature and up to 41°C, the fever can be considered high (the technical term is hyperpyrexia), over 41° is very high (extreme hyperpyrexia).

We must not forget, however, that every person has daily variations in temperature of half a degree, more or less, and that the increase is also influenced by physical exercise, diet and external temperature.

Finally, in children the temperature is higher than in adults.

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How to measure

Doctors, especially pediatricians, suggest using antipyretics when the temperature exceeds 38.5°C. However, it is essential to learn how to measure temperature accurately and, above all, to distinguish between internal and external temperature, depending on the method used to measure it.

The former is usually more than half a degree above the second. We can speak of fever when the body temperature exceeds 37°C if measured by cutaneous route – that is axillary or inguinal – or 37.5°C when measured rectally or oral.

You may also like to read: Hypertension: Causes and long-term effects

The old mercury thermometer, due to the toxicity of the metal, you can choose from a series of latest-generation electronic meters: digital, galinstan, infrared (earphone and front).

  • Digital: Unbreakable, waterproof and fast: the temperature is shown on the display in less than two minutes. They can be used axially, inguinal, oral and rectal, if equipped with a flexible probe.
  • Galinstan: They resemble the old mercury thermometer, but contain an alloy of gallium, indium and tin. The measurement is accurate and can be detected in three minutes by axillary, oral inguinal and rectal.
  • Infrared: The secret lies in a special sensor, which measures the heat radiated by the body in the form of infrared rays. The conically shaped auricular model must be inserted into the external auditory canal: the temperature is considered normal when it oscillates between 36°C and 38°C. The non-contact frontal one, on the other hand, detects the temperature of the front at a distance thanks to an optical pointer. Both models are particularly suitable for children.

Where to measure the temperature

The ideal measurement for newborns is rectal: it is reliable, precise and has the advantage of being fast enough. Naturally, the tip of the thermometer must be covered with a lubricating gel.

When the baby starts to grow, you can opt for oral measurement: the thermometer rests well under the tongue or between the gums and the cheek and waits for 2-3 minutes. In both cases, it is internal temperature, to which we must subtract half a degree to have the correct level.

Adults, on the other hand, can proceed with skin, axillary or inguinal measurements: the thermometer must remain in close contact with perfectly dry skin for a period of time ranging from 3 to 5 minutes.

Practical advice

And to be as accurate as possible, here are some useful tips: measure the temperature in constant conditions, i.e. with the same thermometer, in the same place and, possibly, at the same time: the most indicated times are at morning awakening and late afternoon.

Avoid measuring the temperature in the evening, because it is generally higher than one degree; near meals or after drinking very hot or cold liquids (in this case, allow at least half an hour); after smoking or after exercise.