Why Do I Have Chills?

A walk down a cold, windy street can send a shivery tingle up and down your body, but so can some health conditions, like the flu, kidney stones, or an underactive thyroid.

You get chills when the muscles in your body squeeze and relax to try to make heat. This sometimes happens because you're cold, but it can also be an attempt by your immune system -- the body's defense against germs -- to fight off an infection or illness.

Flu

Your body may use chills to boost its core temperature and kill off the flu virus you've caught. This is why fever and chills often happen at the same time. Although you may feel like you are freezing, your body temperature inside could be turned up as high as 104 F.

If flu is the cause of your chills, you might also have symptoms like:

Most of the time, the flu goes away on its own within 2 weeks. During that time, you should rest and drink lots of fluids. Children under the age of 5, adults over 65, and anyone with a long-term health issue should see a doctor right away.

Infection

Just like with the flu virus, your body can turn on the chills in response to other infections. This may help your immune system kick in faster and work better.

Chills are a common symptom of infections like pneumonia, urinary tract infections (UTI), and malaria.

Besides chills, an infection can also cause symptoms like:

  • Fever
  • Coughing
  • Sore throat or mouth sores
  • Stuffed-up nose
  • Shortness of breath
  • Stiff neck
  • Pain or burning when you pee
  • Diarrhea
  • Throwing up
  • Belly pain
  • Redness, soreness, or swelling in one area

See your doctor if you have these symptoms. You may need medication to treat the infection.

Infection Due to a Kidney Stone

You might get chills because of an infection that starts when you have a kidney stone.

Sometimes minerals and salts stick together to form a hard mass inside your kidney called a kidney stone. This is more likely to happen if you don't drink enough water each day, eat a diet that's high in protein, or have a high body mass index (BMI.)

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If the kidney stone irritates or blocks your urinary tract, it can cause an infection, which could cause chills.

Other symptoms you might get with kidney stones are:

  • Pain in your side, back, belly, or groin
  • Pain when you pee
  • Pink, red, or brown urine
  • Urgent need to pee
  • Pee more or less than you usually do
  • Cloudy urine that smells funny

Call your doctor right away. If your stone doesn't pass on its own, you may need surgery or a treatment that can break it into small pieces.

Hypothermia

If your body loses heat faster than it can make it, your body temperature will start to drop. Under normal conditions, it should be around 98.6 F. If it drops below 95 F, you have what's called hypothermia. Your organs can't function like they should when they're that cold. Chills are your body's attempt to try to warm back up.

Shivering is the first sign of hypothermia. Other symptoms to watch for are:

  • Slurred speech
  • Slowed, shallow breathing
  • Low energy
  • Weakened pulse
  • Feeling clumsy
  • Confusion
  • Bright red, cold skin (in babies)

If you think you or someone you know has hypothermia, call 911. Medical treatment may be needed to raise your body temperature back to normal levels.

Underactive Thyroid

Your thyroid is a butterfly-shaped gland in your neck. It makes a hormone that helps your body stay warm and keeps your organs working like they should. If your thyroid doesn't make enough of this hormone, you have an underactive thyroid, also known as hypothyroidism.

Besides chills without fever, symptoms can include:

There's no cure for hypothyroidism, but you can control it with medicine. Your doctor might prescribe a daily pill that supplies the hormone your thyroid no longer makes.

Hypoglycemia

You get a condition called hypoglycemia when your blood sugar drops to an unsafe level. This is most likely to happen if you have diabetes and your food and medicine get out of balance. Insulin and the oral diabetes medications called sulfonylureas are the most likely to cause hypoglycemia.

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Although it's rare, people without diabetes can get hypoglycemia, too.

If you have hypoglycemia, you can have body chills without fever. Other common symptoms are:

If you catch hypoglycemia early, you can treat it by eating a simple sugar like glucose tablets or gel, hard candies, or juice or sugar soda. If your hypoglycemia is so severe that you become unconscious, a friend or family member that you're with can inject you with glucagon, a hormone that helps control blood sugar.

If you are at high risk for hypoglycemia, you and your family should know how to recognize and treat it. Always let your doctor know if you think you have hypoglycemia, even if you don't have diabetes. If left unchecked, it could cause you to have a seizure or pass out.

WebMD Medical Reference Reviewed by Sabrina Felson, MD on May 21, 2019

Sources

SOURCES:

Mayo Clinic: "Flu Symptoms: Should I see my doctor?" "Kidney Stones," "Hypothermia," "Malaria."

UPMC: "Why Do I Have the Chills?" "Hypoglycemia."

American Thyroid Association: "Hypothyroidism (Underactive thyroid.)"

Evidence-Based Diabetes Management: "The Persistent Complication of Hypoglycemia in Diabetics."

Hormone Health Network: "What is glucagon?" "Non-diabetic hypoglycemia."

Journal of Internal Medicine: "Chills in 'early sepsis:' Good for you?"

National Kidney Foundation: "Kidney Stones."

CDC: "Protect: Know the Signs and Symptoms of Infection."

Better Health Channel/Victorian Government (Australia): "Infections-Bacterial and Viral."

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