Fevers are caused by chemicals called pyrogens flowing in the bloodstream. Pyrogens make their way to the hypothalamus in the brain, which is in charge of regulating body temperature. When pyrogens bind to certain receptors in the hypothalamus, body temperature rises.

What causes a rise in body temperature?

The most common causes of fever are infections such as colds and stomach bugs (gastroenteritis). Other causes include: Infections of the ear, lung, skin, throat, bladder, or kidney. Heat exhaustion.

Why does body temperature rise without fever?

There are many reasons why someone might feel hot but have no fever. Environmental and lifestyle factors, medications, age, hormones, and emotional state all have an impact. In some cases, feeling continuously hot may signal an underlying health condition.