Fever in Adults
A fever is a body temperature that is higher than normal. A normal temperature can vary from person to person, but it is usually around 98.6 F. (37)
A fever is not a disease. It is usually a sign that your body is trying to fight an illness or infection.
In general, a baby has a fever when their body temperature exceeds 100.4°F (38°C). A child has a fever when their temperature exceeds 99.5°F (37.5°C). An adult has a fever when their temperature exceeds 99–99.5°F (37.2–37.5°C).
Normal body temperatures vary depending on many factors, including age, sex, time of day, ambient temperature, activity level, and more. A raised temperature is not always a fever. For example, the temperature of a healthy person rises when he or she exercises, but this is not considered a fever, as the set point is normal.
Medically, a person is not considered to have a significant fever until the temperature is above 100.4 F (38.0 C).
Fever is not considered medically significant until body temperature is above 100.4 F (38 C), which is the temperature considered to be a fever by medical professionals.
Anything above normal but below 100.4 F (38 C) is considered a low-grade fever.
There are so many classifications.
What I personally adopt is the following:
Low grade = 37.3 -37.9 C
Moderate grade = 38 – 39C
High grade = 39.1 – 41C
Hyperthermic fever = >41C
The other classifications are more difficult to use in day-to-day assessment: