People typically associate shivering with being cold, so you may wonder why you shiver when you have a fever. Shivering is part of the body’s natural response to an illness. When a person shivers, it helps their body temperature rise, which helps fight off a virus or a bacterial infection.

Still, it’s important to know what to do if you’re feeling hotter than normal, and your body is shaking with chills. Read on to learn more about shivering and fevers.

Shivering helps the body warm itself.

When you shiver, your muscles contract and relax in rapid succession, and all those little movements can create heat. It’s an involuntary response triggered by your immune system reacting to an infection or a cold environment.

An increase in body temperature can help your body fight infections because infections don’t survive as well above your normal temperature of 98.6°F (37.0°C).

The part of your brain that sets your body’s temperature is called the hypothalamus. When the body has an infection, the hypothalamus responds by moving the “set point” for a higher temperature.

The muscles in your body respond by contracting and relaxing faster, which helps your body reach this higher temperature more quickly. Once your body temperature reaches its new set point, your shivering should stop.

Other conditions, such as a sudden drop in your blood sugar levels, can also bring on shivering. You may also experience shivering after surgery as a response to the anesthesia wearing off.

Additionally, certain types of anesthesia can interfere with your body’s usual temperature regulation system. When paired with a cool operating room environment, a decrease in body temperature can lead to shivering.

Can you have a fever without shivering?

You may have a fever without shivering and the chills, too. Conditions that may trigger a fever include:

Not every fever needs treatment.

According to Mayo Clinic, rest and fluids are usually enough to treat a fever in adults and infants over the age of 2, unless the fever reaches above 102°F (38.9°C).

This treatment also applies to babies between 3 and 6 months old, as long as they are not acting out of the ordinary. Treat children ages 6 to 24 months in the same way, unless the fever stays above 102°F (38.9°C) rectally for more than a day.

When rest and fluids aren’t enough, try acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). Read the labels carefully, especially when treating a child.

You should also check with a doctor or a pharmacist if you have any questions about dosing or combining medications.

Do not give medications to infants less than 6 months old.

Speak to a doctor immediately if an infant under 3 months old has a rectal temperature of 100.4°F (38°C) or higher.

Mild vs. high fever in adults

  • Mild or low-grade fever: A temperature between 99.5°F (37.5°C) and 100.9°F (38.3°C)
  • High or high-grade fever: Temperature over 103.0°F (39.4°C)
Healthline

If you have a mild fever with shivering, you don’t necessarily need to see a doctor or take a fever-reducing medication. You might prefer to get comfortable and wait it out. You can try:

  • resting with a light sheet, rather than a heavy blanket, which can continue to raise your body temperature
  • putting on an extra layer of clothes, like a sweatshirt, that you can remove if you start to overheat
  • turning up the temperature in your home
  • drinking plenty of fluids

When other serious signs accompany a fever and chills, you should see a doctor as soon as possible. These include:

  • a stiff neck
  • confusion
  • irritability
  • sluggishness
  • a bad cough
  • shortness of breath
  • severe abdominal pain

You should also seek medical help if:

  • you’re an adult, and you have a temperature that remains above 103°F (39.4°C) for more than an hour following home treatment
  • you’re an adult, and you have a fever that lasts more than 3 days
  • a baby younger than 3 months has a rectal temperature of 100.4°F (38.0°C) or higher
  • a child between the ages of 3 months and 1 year has a fever above 102.0°F (38.9°C) that lasts for more than 24 hours

If you feel your temperature starting to rise into a fever, and you’re shivering, keep in mind that your body is probably responding to an infection.

Rest and fluids are the best ways to help your body recover, but you can take acetaminophen or ibuprofen as well, especially if your temperature rises above 102°F (38.9°C).

Pay close attention to other signs, which may indicate that you need to see a doctor.

If it’s your child who is shivering with what feels like a fever, be sure to get an accurate temperature reading, so you’ll know whether to get your little one to a doctor immediately.