By definition, fever is an increase in body temperature above 38 ° C. The best way to get an accurate fever measurement in a baby is with the rectal thermometer, but there are reliable forehead or ear thermometers.

Fever is a frequent symptom, which is not dangerous and which corresponds to a normal reaction of the organism in the event of infection but not only like for example during a sunstroke or a heat stroke.

In an infant, on the other hand, fever can be a sign of a condition that needs to be treated quickly. Thereby :

• a baby under 3 months with a rectal temperature of 38 ° C should be seen by a doctor or pediatrician the same day (emergency room if necessary)
• a 3 to 6 month old baby with a temperature of 39 ° C or who has had a fever for more than 48 hours should be seen by a doctor

The behavior of the baby should also alert: if he takes less than half of his bottles or feeds, if he is amorphous, that it is difficult to wake up, that his neck seems stiff, or that he is having difficulties. to breathe, seek medical attention immediately.

Any infection can cause a fever in a baby, from the common cold to very serious infections like meningitis. The cause can be viral or bacterial.

Teething can also, on occasion, be associated with an outbreak of fever but rarely beyond 39 °.

Before the age of 3 months, fever should never be considered a trivial symptom, as the risk of serious bacterial infection is high (around 12 to 18%). Going to the pediatric emergency room in the hospital and a complete blood test is necessary. 

Between 3 and 6 months, it is also advisable to consult a doctor immediately, even if the general condition of the baby is good.

After this age, since fever is an extremely common symptom and is most often caused by viral infections, it is advisable to wait 72 hours before consulting (except, of course, if the child shows worrying signs such as a decrease food intake, poor tolerance of fever such as breathing difficulties). If the fever persists after 3 days or the child’s condition worsens, seems uncomfortable, or complains of headache and stiff neck, do not hesitate to seek immediate medical attention.

Some of the most common causes of fever in babies include, but are not limited to:

• urinary tract infections and acute pyelonephritis
• respiratory viral infections (especially in winter) such as bronchiolitis
• gastroenteritis
• viroses with dermatological manifestations such as roseola or chickenpox
• ear infections and other ENT infections
• pneumonia
• meningitis
• bacteremia (infections of the blood)

The fever is not dangerous as such, except in exceptional cases where it exceeds 41 ° C. On the other hand, especially in newborns, it can be indicative of a serious infection and should therefore alert.

In a child suffering from a chronic disease or having a weakened immune system, the fever should also prompt to see a doctor quickly.

In some children, the fever can cause seizures called febrile, very impressive but without danger. They affect about 3% of babies and most often occur between 9 months and 3 years (up to 5 years), with a peak between 18 and 24 months.

Another major risk posed by fever is dehydration: increased water loss through sweating can lead to dehydration, especially if the baby is not feeding and has digestive problems (diarrhea, vomiting).

Again, if the child is active and toned, playing, not drowsy, and not crying or moaning excessively, you should be reassured.

As we have seen, before 6 months, you must consult without delay. If a bacterial infection is found, treatment with antibiotics should be initiated.

In other cases, while waiting to see a doctor (which is not always necessary in older children with a viral infection), certain measures can improve the comfort of the child. If the fever is well tolerated, there is no need to lower it absolutely: it allows the body to fight against the infection and therefore has its biological importance.

Among the basic measures:

• avoid covering the child too much
• ventilate the room and do not overheat it (18-19 ° C)
• get the child to drink as often as possible (water, rehydration solutions, milk or breastfeed often)

It is not advisable to take a lukewarm bath, as this increases the discomfort with a risk of seizures and thermal shock.

If needed, the child can be given an antipyretic drug. Be careful to respect the doses, to favor a single drug (do not combine them without medical advice) and to respect the recommended time between doses.

Warning ! Do not give ibuprofen to a baby under 6 months old, and never give aspirin (= acetylsalicylic acid) to a child without medical advice.

• Before 6 months, only paracetamol (= acetaminophen) is authorized (unless medical advice to the contrary)
• Ibuprofen, a non-steroidal anti-inflammatory drug (= NSAID), can be offered from 6 months

The alternation of paracetamol and ibuprofen is not recommended, because no study has shown its benefit.

Although considered not very virulent in children, severe infections of COVID 19 are rare in children, however it can be mentioned.

• In the event of close contact with a person carrying a virus
• In case of prolonged fever> 4 days
• In case of colds outside the winter period

It is rare to test a baby for covid 19 but the pediatrician will not hesitate to suggest it in the event of a visit to the emergency room or in the event of an unexplained fever.

• The rectal route is strongly recommended because it is the closest to the core temperature