2015-01-20 13:30:00
Fever means a augmentation core temperature above 38°C, in the absence of intense physical activity and in a temperate ambient temperature. It is generally not dangerous, underlines the High Authority of Health (HAS) (Source 1).
What temperature is considered a fever?
Normal body body temperature fluctuates 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). It is often accompanied by a feeling of cold and chills more or less intense.
We speak of fever from 38 ° C. Most of the time, the cause of the fever is a viral, bacterial or parasitic infection (flu, angina, gastro…). But it can also be caused by other diseases – inflammatory, tumoral –, hyperthyroidism or, simply, by intense exercise or heat stroke.
Is an illness more serious if it is accompanied by fever?
The fever reflects a our body’s defense mechanism. “This ‘increases the ‘thermostat’ in the brain to prevent the multiplication of microbes and thus help the white blood cells to fight against infection”, indicates François Baumann, general practitioner in Paris. It is a symptom of the disease. That is why you don’t have to drop it.
If it reflects rather a good immune system, this reaction can also constitute an alarm signal. Example: when a fever occurs during a nasopharyngitis of viral origin, it is the sign of a bacterial superinfection.
Fever: from how much is it recommended to consult?
The doctors consider that there is nothing to worry about, as long as body temperature does not exceed 38.5°C. However, beyond 48 hours, an abnormally high temperature requires a medical consultation.
A urinary tract infection is commonplace in young women, but if it is accompanied by a slight fever, this can reflect more serious kidney damage, warns Dr. François Baumann.
Below 40°C, fever does not threaten a healthy young person. Above 38°C, more fragile people should seek medical advice without delay. Are concerned in the first place:
- Children under one year old;
- Elderly people who become dehydrated very quickly;
- Pregnant women ;
- Patients suffering from chronic disease (diabetes, cardiac or respiratory disorders);
- People on immunosuppressive drugs, after a transplant, for example.
The consequences of too high a fever
Extreme temperature rise (>41°C) can be harmful, says Dr. Larry M. Bush in an article published in 2022 (Source 2). “At this temperature, a protein denaturation occurs and the inflammatory cytokines that activate the inflammatory cascade are released. Thus, a cellular dysfunction occurs, favoring at an ultimate stage a failure of many organs“, indicates the latter.
Fever can also cause decompensation of heart or respiratory failure in adults, and worsen the mental state of patients with dementia.
How do you know if you have a fever? Which thermometer to choose?
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”, specifies Dr Olivier Darrerye, general practitioner.
Electronic thermometers, both inexpensive and very accurate
The probe is inserted rectally, orally, or under the armpit, and the display shows the temperature in less than a minute. Their only drawback is that they may become less reliable after a few years.
For who ? The whole family. If the rectal route remains recommended for toddlers, adults and children over 5 years old can opt for a measurement in the mouth or under the armpit. The electronic thermometer must then be placed under the tongue or wedged under the armpit. This last measurement can however be influenced by the outside temperature.
Forehead 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 in children. They also have the advantage of being very hygienic and limit the risk of contamination. The only drawback: they are not always very precise.
Infrared ear thermometers
They use the same infrared technology to take the temperature inside the ear, but with great precision. Suitable for children over 2 years old (below this age, the conformation of the ears of small children makes it difficult to grip).
Gallium thermometers
They have replaced banned mercury thermometers. They contain a assembly of heat sensitive metals who climbs along a graduated ladder. Their use is identical to that of electronic thermometers.
How to lower the fever? What medicine to use?
When to take medicine?
There are no official recommendations on the temperature from which to lower the fever. It is above all a matter of comfort : if the person tolerates the fever well, do not try to reduce it. Fever is indeed a natural mechanism that aims to fight against infection.
What medicine to use for fever?
To lower fever, paracetamol should always be taken in first intention, 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. approximately 15 mg/kg every 6 hours (minimum period of 4 hours between 2 doses).
In case of contraindication to paracetamolthe use of an NSAID (non-steroidal anti-inflammatory drug) is possible:ibuprofen (in children over 3 months) and ketoprofen (in children over 6 months). In children, taking an NSAID should be done after medical advice.
Aspirin and all other NSAIDs are contraindicated in pregnant women from the sixth month of pregnancy. NSAIDs should be avoided in case of chickenpox.
It is also contraindicated to combine several treatments.
Regardless antipyretic treatment used, respect the doses and the intervals of doses indicated on the leaflet. Do not prolong the treatment beyond three days without medical advice.
What to do when a baby has a temperature?
Fever is generally not dangerous in children, indicates the HAS. “The febrile child may present with Changing behaviour (apathy, anorexia, headaches, decrease in activities, etc.) which testifies, in the same way as the fever, to its immune response. This situation can be uncomfortable and therefore justifies treatment”.
And lukewarm bath, at 2°C below body temperature, has long been recommended to prevent seizures in babies. But these seizures affect less than 5% of toddlers, and this parade is now considered too brutal and is now not recommended.
Pour bring down the fever and relieve the baby, three simple measures, to be combined with drug treatment, are recommended:
- Do not cover the child too much;
- Make him drink regularly;
- Do not increase room temperature.
The paracetamol is the only medication recommended as first-line treatment for toddlers. Doctors recommend it from 38.5° of fever. Use in monotherapy (without other drugs) for 24 hours. If symptoms and discomfort persist, further medical advice is imperative.
A fever is said acute when it has been evolving for less than 5 days in infants, and less than 1 week in older children. Beyond that, we talk about prolonged or persistent fever.
When should you go to the emergency room?
However, the baby must be taken to the emergency room:
- If it is less than 3 months old;
- If he convulses for the first time;
- If he has difficulty breathing;
- If spots appear on his skin;
- If he seems dejected;
- Or if he cries without stopping.
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