It is lowest in the early morning and highest in the late afternoon—sometimes reaching 99.9° F (37.7° C). Similarly, a fever does not stay at a constant temperature.

Both are highly related but they are not the same. The Key Difference Between Heat and Work is that Heat is the transfer of thermal energy between systems, while work is the transfer the mechanical energy between two systems.

Heat transfer is conduction, convection or radiation. Heat can cause a change in body’s temperature by changing the internal energy of the body. Internal energy of a body is the total energy (Kinetic and potential) of its molecules.

Do Get Plenty of Rest It’s one reason why doctors prescribe rest as part of a fever treatment regimen. Fevers also tend to make you feel tired, so the need for rest makes sense.

A viral fever refers to any fever that results from a viral infection, such as the flu or dengue fever. While most viral fevers resolve on their own within a day or two, some are more severe and require medical treatment. If your temperature starts reading 103°F (39°C) or higher, it’s time to call a doctor.

High fever (>39.5 °C) is often associated with influenza A virus infections, occurring in more than 50% of children. Adenovirus infection causes fever exceeding 40 °C in about 20%, while fever in rhinovirus infection is usually absent or mild. Fever associated with respiratory virus infection may last for 3–5 days.

You get a fever because your body is trying to kill the virus or bacteria that caused the infection. Most of those bacteria and viruses do well when your body is at your normal temperature. But if you have a fever, it is harder for them to survive. Fever also activates your body’s immune system.

Checking for a fever without a thermometer

1. Touching the forehead. Touching a person’s forehead with the back of the hand is a common method of telling whether or not they have a fever.
2. Pinching the hand.
3. Looking for flushing in the cheeks.
4. Checking urine color.
5. Looking for other symptoms.