Mercury has dropped and with it respiratory diseases such as the flu, which can cause discomfort and even fever, have increased. However, in many cases patients are not sure what temperature they can be considered to have a fever at. Firstly, the Spanish Society of General and Family Physicians (SEMG) warns that normal body temperature is different for each person and also varies throughout the day. Most commonly, it is highest between 4:00 p.m. and 8:00 p.m. and tends to drop until 6:00 a.m. Once this specification has been made, SEMG indicates that the limit for a normal body temperature is 37ºC measured in the armpit. From this temperature and up to 37.8ºC, doctors consider it feverish and beyond this it is referred to as fever. When is it fever? Up to 37ºC is normal Between 37ºC and 37.8ºC is fever More than 37.8ºC is fever These thresholds are the same for children and adults. However, experts explain that fever is still a symptom, so each patient feels its effects differently. Given this, they recommend controlling the temperature by the same route at different times to follow its evolution and thus guide us by objective measurements. Even so, the Spanish Pediatric Association considers that a child has a fever when their body temperature exceeds 38ºC in the rectum or 37.5ºC in the armpit. Doctors remember that fever is our body’s defense mechanism against an infection that comes when a pathogen enters the body. What our system does is increase the temperature to activate the immune system to destroy germs. How to measure and treat fever? As for the measurement, the most reliable thermometer is the digital one and it must be carried out in the axillary area. The rectal temperature is usually 0.5 ºC above the axillary. Physicians recommend staying hydrated and taking care of caloric intake, an ambient temperature of around 22ºC, not being very warm and resting. In addition to this, patients can take antipyretics such as paracetamol or ibuprofen.