A fever can feel alarming—hot skin, chills, fatigue, maybe even a headache that won’t quit. But in most cases, a fever isn’t the enemy. It’s actually a sign that your body is doing its job.
Let’s break down what a fever really is, why it happens, and when you should (and shouldn’t) worry.
What Is a Fever?
A fever is a temporary rise in body temperature, usually above 38°C (100.4°F). Your normal temperature can vary throughout the day, but when it climbs beyond this range, it’s typically because your immune system is responding to something—most often an infection.
Think of a fever as your body’s internal thermostat being turned up on purpose.Why Does the Body Cause a Fever?
When viruses or bacteria invade, your immune system releases chemicals called pyrogens. These tell your brain to raise your body temperature. Why? Because many germs struggle to survive in hotter conditions, and higher temperatures help immune cells work more efficiently.
In short:
A fever is your body fighting back.
Common Causes of Fever
Fever can be triggered by many things, including:
Reactions to vaccines or medications
Viral infections (like the flu or common cold)
Bacterial infections (such as strep throat or urinary tract infections)
Inflammatory conditions
Heat exhaustion