“A fever happens when your body is trying to fight an infection. It’s not a sickness itself but a sign that your immune system is working,” explains Dr. Iroko Anita, a certified medical doctor. When germs like bacteria or viruses get into your body, the brain’s hypothalamus, which controls temperature, makes your body heat up. This rise in temperature is called a fever.

Your immune system produces chemicals called pyrogens that tell the hypothalamus to increase your body’s temperature. This response not only slows down the growth of harmful microorganisms but also boosts your immune response. “It’s a natural process that shows your body is doing what it’s supposed to,” Dr. Iroko Anita adds.

Why Your Temperature Goes Up

The hypothalamus works like a thermostat. Dr. Iroko Anita explains, “When your brain detects germs, it raises your body’s temperature to make it harder for them to survive.” Normal body temperature is usually between 97.7°F and 99.5°F (36.5°C to 37.5°C). A fever is when your temperature is 100.4°F (38°C) or higher.

This process helps create an environment that makes it difficult for viruses and bacteria to thrive. Higher temperatures also activate special cells in your immune system, such as white blood cells and proteins, which attack and destroy invaders more effectively.

Common Signs of a Fever

When you have a fever, you might notice:

Feeling cold and shivering
Sweating
Feeling very tired
Headaches
Achy muscles
Not feeling hungry
Mild dizziness or weakness

“These are signals from your body that it’s fighting an infection,” says Dr. Iroko Anita. In some cases, you may also experience irritability, trouble sleeping, or a slight increase in heart rate. These symptoms usually disappear once the fever resolves.

How Fevers Help Your Body

Even though fevers can feel uncomfortable, they have a purpose. Dr. Iroko Anita says, “A fever helps your body’s immune system by making more white blood cells and antibodies to fight infections.” Also, many germs can’t grow as well when your body’s temperature is higher.

Fever also stimulates the production of interferons, which are proteins that help the immune system communicate more effectively. “It’s a built-in defense mechanism that’s essential for fighting off illnesses,” Dr. Iroko Anita explains.

When Fevers Are Serious

Most fevers go away on their own, but some can be dangerous. Dr. Iroko Anita warns, “If your temperature is over 104°F (40°C), it can cause problems like dehydration, confusion, or seizures, especially in kids.” You should see a doctor if:

The fever lasts more than three days
There are serious symptoms like trouble breathing or nonstop vomiting
A baby younger than three months has a fever of 100.4°F (38°C) or more
The fever is accompanied by a severe rash, stiff neck, or persistent pain

Dr. Iroko Anita also notes that repeated fevers or fevers that come and go might indicate an underlying condition that needs further investigation.

How to Take Care of a Fever at Home

Dr. Iroko Anita suggests simple ways to feel better if you have a mild fever:

“Drink plenty of fluids to stay hydrated.”
“Rest so your body can recover.”
“Take over-the-counter medicine like acetaminophen or ibuprofen to lower the fever, but always follow the instructions.”

She also says not to use alcohol rubs or cold baths because these can make you shiver and increase your temperature. Instead, a lukewarm sponge bath can help you cool down more gently.

Additionally, wear lightweight clothing and use light blankets. Avoid heavy covers, as they may trap heat and worsen discomfort. Eating small, easy-to-digest meals can also provide the energy your body needs to heal.

When to See a Doctor

Dr. Iroko Anita advises, “If you’re not sure what’s causing the fever or if it comes with severe symptoms, talk to a doctor right away.” Getting help early can find the problem and stop it from getting worse.

Other signs that you should seek medical care include a high fever that does not respond to medication, unusual drowsiness, or a persistent lack of energy. In rare cases, fevers can signal serious illnesses like meningitis or other systemic infections that need immediate treatment.

The Bottom Line

A fever usually shows that your immune system is doing its job, but it’s important to watch how high and how long it lasts. Dr. Iroko Anita says, “Most fevers aren’t serious, but knowing when to get medical help is important.” If you’re worried about a high or long-lasting fever, see a doctor to figure out the next steps.

While fevers can be uncomfortable, they are a sign that your body is actively protecting itself. Understanding how to care for yourself and when to seek help can make managing a fever much easier.