Fever accompanies many of our infections, but the slightest outbreak sometimes leaves us distraught. Here are the questions you should ask yourself when your temperature or your child's temperature reaches 38, 39, 40 °C . And here are our answers.

Fever:, at, what, temperature, should, we, worry?

Is fever always a sign of infection?

Normal body temperature varies between 36°C and 37.2°C depending on the person, the female cycle (it rises with ovulation) and the time of day (it rises in the evening).

 Fever is considered to be above 38°C. Most of the time, it is caused by a viral, bacterial or parasitic infection. But it can also be caused by other illnesses - inflammatory, tumourous -, hyperthyroidism or simply by intense exercise or heat stroke.

Is an illness more serious if accompanied by a fever?

Fever reflects our body's defense mechanism. It "increases the "thermostat" in the brain to prevent the multiplication of microbes and thus help the white blood cells to fight the infection," says François Baumann, a general practitioner in Paris. That's why you don't necessarily have to drop it. 

If it is a sign of a good immune system, it can also be a warning signal. Example: When a fever occurs during a viral rhinopharyngitis, it is a sign of a bacterial superinfection. 

 Below 39°C, when should I consult?

Doctors consider that there is nothing to worry about as long as the temperature does not exceed 38.5°C.

However, beyond 48 hours, an abnormally high temperature requires a consultation.

  "A urinary tract infection is common in young women, but if it is accompanied by a slight fever, it can indicate a more serious kidney problem," warns Dr. François Baumann.

Who is exposed in case of high fever?

Below 40°C, a fever does not threaten a young healthy person.

However, above 38°C, more fragile people should seek medical advice without delay. Are concerned in the first place : 

    children under one year of age ;
    the elderly who dehydrate very quickly;
    pregnant women;
    patients with chronic diseases (diabetes, heart or respiratory problems);
    people on immunosuppressive drugs, for example, after a transplant.

Which thermometer should I choose to properly measure fever?

The temperature can be measured under the armpit, in the ear, on the forehead, in the mouth or in the anus". The rectal route remains the reference for doctors," says Dr. Olivier Darrerye, a general practitioner.

Electronic thermometers are both inexpensive and highly accurate.

The probe is inserted rectally, buccally, or under the armpit, and the display shows the temperature in less than a minute. Their only drawback is that they may prove less reliable after a few years. For whom? The whole family. While the rectal route is still recommended for toddlers, adults and children over the age of 5 can choose to have their temperature measured in the mouth or under the armpit. The electronic thermometer must then be placed under the tongue or wedged under the armpit. The latter measurement can be influenced by the outside temperature, however.

Frontal infrared thermometers.

Equipped with an infrared probe, they perform a series of measurements in less than a second and display the highest result. They are sometimes used without contact on the forehead or temple, which makes them much more convenient than electronic thermometers, especially for children. They also have the advantage of being very hygienic and limiting the risk of contamination. The only drawback is that they are not always very accurate.

Infrared ear thermometers

They use the same infrared technology to take the temperature inside the ear, but with great accuracy. Suitable for children over 2 years old (below this age, the conformation of the ear of the little ones makes the taking complicated).

Gallium thermometers

They have replaced the banned mercury thermometers. They contain an assembly of heat-sensitive metals that climbs up a graduated scale. Their use is identical to that of electronic thermometers.   

               Add 0.5 °C if you choose to measure the temperature in the mouth, or 1 °C under  the armpit. The fever threshold is set at 38°C.

What medicine should I use for fever?

To lower fever, paracetamol should always be taken as a first-line medication because it has the fewest side effects:

    in adults: the maximum recommended dose is 4 g per day, to be divided between 4 doses;
    in children: 60 mg/kg/day, to be divided into 4 or 6 doses, i.e. about 15 mg/kg every 6 hours (minimum delay of 4 hours between 2 doses).

In case of contraindication to paracetamol, the use of an NSAID (non-steroidal anti-inflammatory drug) is possible: ibuprofen (in children over 3 months old) and ketoprofen (in children over 6 months old). In children, NSAIDs should be taken only after medical advice.

Aspirin and all other NSAIDs are contraindicated in pregnant women after the sixth month of pregnancy. NSAIDs should be avoided in case of chickenpox.

It is also contraindicated to combine several treatments.

Regardless of the antipyretic treatment used, follow the doses and dosing intervals indicated in the package insert. Do not extend treatment beyond three days without medical advice.
                Covid-19: It is not recommended to start treatment with anti-inflammatory drugs to reduce fever as these drugs may aggravate the coronavirus infection. In case of fever, paracetamol is preferred.

What to do when a baby has a temperature?

A lukewarm bath, at 2°C below body temperature, has long been recommended to avoid convulsions in babies. But these seizures affect less than 5% of toddlers, and this parade is now considered too brutal and is now discouraged.

To lower the fever and relieve the baby, three simple measures, to be associated with a medicamentous treatment, are recommended :

    not to cover the child too much,
    make him drink regularly,
    do not increase the room temperature.

Paracetamol is the only drug recommended as a first-line treatment for a toddler. To be used as monotherapy (without other medications) for 24 hours. If symptoms and discomfort persist, a new medical opinion is imperative.

When should I go to the emergency room?

However, the baby must be taken to the emergency room:

    If the baby is less than 3 months old;
    if he has a seizure for the first time;
    if the baby is having trouble breathing;
    if spots appear on his skin;
    if he seems to be down;
    or if he cries without stopping.