Fever facts for kids

A fever happens when your body temperature gets hotter than 37.5 degrees Celsius (99.5 Fahrenheit). Your normal body temperature can change a bit depending on things like your age and how active you are. Usually, it's around 37 degrees Celsius (98.6 F).

When you are sick, your body's immune system works hard to fight off the disease. This fight often makes your body temperature go up. A fever is actually your body's way of defending itself against germs. The higher temperature makes it harder for germs to live and grow.

A temperature around 38 °C (100.4 F) is called a low-grade fever. If it goes above 39 °C (103 F), it's considered a high-grade fever.

Children often have higher fevers than adults because their immune systems are still developing. Babies usually have the highest normal temperature, which slowly drops as people get older. Some animals, like rabbits and cats, also have a naturally higher body temperature than humans.

Sometimes, a very high fever can be serious and needs medical help right away. If your temperature reaches 42 °C (107.6 F) or higher, your body's organs can start to get damaged.

What Causes a Fever?

A fever is a common symptom of many different health conditions. It means your body is reacting to something.

• Infections: This is the most common cause. Fevers can happen with illnesses like COVID-19, dengue, influenza (the flu), gastroenteritis (stomach bug), Lyme disease, malaria, or even skin infections like abscesses.
• Immune System Issues: Sometimes, fevers are linked to conditions where your immune system doesn't work quite right, like inflammatory bowel diseases or rheumatoid arthritis.
• Tissue Damage: If parts of your body are damaged, for example, after surgery or an injury, you might get a fever.
• Cancers: Certain types of Cancers, especially blood cancers like leukemia, can cause fevers.
• Other Conditions: Fevers can also be a sign of Metabolic disorders like gout.

It's important to know that Teething in babies does not cause a fever.

How Fevers Feel

When you have a fever, you might also feel other symptoms. These can include:

• Feeling very tired or having low energy (called lethargy).
• Feeling sad or down (like depression).
• Not wanting to eat (loss of appetite).
• Feeling very sleepy.
• Being more sensitive to pain (called hyperalgesia).
• Feeling thirsty or dehydrated.
• Having trouble focusing or concentrating.

Sometimes, when you sleep with a fever, you might have very vivid or confusing nightmares, which people often call "fever dreams." If a fever is very high, it can sometimes cause delirium, which means you might feel confused or even see things that aren't there (hallucinations).

Different Types of Fever Patterns

Doctors have noticed that fevers can follow different patterns. These patterns can sometimes give clues about what might be causing the illness.

• Continuous Fever: The temperature stays high and doesn't change much (less than 1 °C) over 24 hours. Examples include bacterial pneumonia or typhoid fever.
• Intermittent Fever: The fever comes and goes, with periods where the temperature returns to normal. This pattern is often seen in malaria.
• Remittent Fever: The temperature stays above normal all day but goes up and down by more than 1 °C in 24 hours.
• Fever of Unknown Origin: This is a fever that doctors can't explain even after many tests.
• Neutropenic Fever: This type of fever happens in people who have a very weak immune system, often because of treatments like chemotherapy. It's serious because the body can't fight off infections well.

Taking Care of a Fever

Most of the time, a fever doesn't need special treatment, and people usually get better on their own. Even if it feels uncomfortable, a fever rarely gets dangerously high without treatment. Brain damage usually doesn't happen until temperatures reach about 42.0 C (107.6 F). It's rare for an untreated fever to go above 40.6 C (105.1 F).

Some people think that fevers are always bad and need to be lowered, but this isn't always true. For most people, letting the fever run its course can help the body fight the infection.

Simple Ways to Feel Better

• You can try sponging or bathing with lukewarm (not cold!) water to help cool down.
• Using a fan or air conditioning might also help you feel more comfortable.
• If a fever gets extremely high (like hyperpyrexia), doctors might use aggressive cooling methods, such as ice packs or even an ice water bath.
• It's always important to drink plenty of fluids to stay hydrated when you have a fever.

Medications for Fever

Medicines that lower fevers are called antipyretics.

• The medicine ibuprofen is good at reducing fevers in children. It often works better than acetaminophen (also known as paracetamol).
• You can safely use ibuprofen and acetaminophen together for children with fevers.
• Aspirin is generally not recommended for children and young adults (under 16 or 19, depending on the country). This is because it can cause a serious condition called Reye's syndrome.

Using both paracetamol and ibuprofen at the same time, or switching between them, can be more effective at lowering a fever than using just one. However, it's not clear if this makes children feel more comfortable. How well a child responds to these medicines doesn't tell doctors if they have a serious illness or not.

See also

In Spanish: Fiebre para niños