Chills are your body's way of trying to adjust its temperature. For instance, a walk down a cold, windy street can trigger this response. Or, they can be an attempt by your immune system -- the body's defense against germs -- to fight off an infection or illness such as the flu or kidney stones. Certain conditions such as an underactive thyroid or anemia can also cause chills.
You get chills when the muscles in your body quickly squeeze and relax to try to make heat. Chills are involuntary, meaning you can't control them. When you have chills, you may have symptoms such as:
- Shivering
- Trembling
- Shaking
- Chattering teeth
- Goosebumps
If you have a fever or a serious infection, you may have chills and sweats at the same time or other symptoms including:
- Body aches
- Clamminess
- Fatigue
- Sore throat
- Headache
- Nausea
Causes of Chills
Your body temperature can vary for many reasons, such as exposure to cold, a long workout, or sickness. When your core body temperature drops, chills are the body's way of returning it closer to normal. The average body temperature is 98.6 F but can range from 97 to 99 F.
Chills With Fever
You can get chills with or without a fever. If you do have a fever with chills, you may have an infection or virus.
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 as high as 104 F.
If flu is the cause of your chills, you might also have symptoms such as:
- Sore throat or cough
- Runny or stuffed-up nose
- Muscle aches
- Fatigue
- Headache
- Nausea
- Throwing up
- Diarrhea
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
Your body can have chills in response to infections such as pneumonia, urinary tract infections (UTIs), and malaria. This helps your immune system kick in faster and work better.
An infection can cause chills and other symptoms such as:
- 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.
Kidney stone infection
You might get chills because of a kidney stone infection.
Sometimes, minerals and salts stick together to form a hard mass inside your kidney called a kidney stone. You are more likely to get kidney stones 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).
If the kidney stone irritates or blocks your urinary tract, it can cause an infection with symptoms including chills and:
- Pain in your side, back, belly, or groin
- Pain when you pee
- Pink, red, or brown urine
- An urgent need to pee
- Peeing more or less than you usually do
- Cloudy urine that smells funny
If you think you might have a kidney stone, call your doctor right away. If your stone doesn't pass on its own, you may need surgery or treatment to break it into small pieces.
Chills Without Fever
You may have chills without fever due to many reasons including medical conditions that lower your body temperature.
Cold weather
When you are outdoors in cold weather, your body can lose heat faster than it produces it. Chills are your body's way of trying to create warmth to bring your temperature back to normal.
Hypothermia
If your body loses heat faster than it can make it, your body temperature will start to drop. If your temperature 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.
Chills from being cold are different from those caused by hypothermia, which is a severe medical condition that can lead to unconsciousness and death. You are more likely to get hypothermia if you've been in extremely cold weather for a long period. But you can also get hypothermia in cool weather if you've been in the rain or submerged in water, like in a pool.
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 to normal levels.
Underactive thyroid
Your thyroid is a butterfly-shaped gland in your neck. It makes hormones that help your body stay warm and keep your organs working well. If your thyroid doesn't make enough of these hormones, you have an underactive thyroid, also known as hypothyroidism.
Besides chills without fever, symptoms can include:
- Fatigue
- Dry skin
- Feeling absent-minded
- Depression
- Constipation
There's no cure for hypothyroidism, but you can control it with medicine. Your doctor might prescribe medicines that supply the hormones 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 can cause hypoglycemia.
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 include:
- Anxiety
- Trembling
- Weakness
- Clammy skin
- Sweating
- Hunger
- Nausea
- Feeling sleepy
If you catch hypoglycemia early, you can treat it by eating simple sugars such as glucose tablets or gel, hard candies, 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.
Medication
Some medicines, including antidepressants, migraine medications, and illicit drugs, can cause chills when you:
- Start taking them
- Increase your dose
- Take more than the prescribed amount
- Suddenly stop taking them (withdrawal)
Anemia
Iron-deficiency anemia, the most common type of anemia, affects your red blood cells. Your body uses iron to make hemoglobin, a protein that carries oxygen to your tissues and provides energy to your body. When your iron is low (anemia), you can feel tired, dizzy, and weak. You may also feel colder than usual and get chills.
How to Get Rid of Chills
If you have chills from cold weather, you can go to a warmer place, put on heavier clothing, or drink hot beverages to increase your body temperature.
If your chills are related to a medical condition, the treatment for chills will depend on their cause. This can include:
- Antibiotic or antiviral prescriptions from your doctor
- Over-the-counter medications to lower your fever
- Iron supplements (for anemia)
When to See a Doctor for Chills
Talk to your doctor if you have chills that don't go away when you try to warm up, or if you have other symptoms with chills, such as:
- Intense fatigue
- Chest pain
- Unusual or severe abdominal pain
- Difficulty breathing
Contact your doctor if you have a very low or high body temperature with chills. This includes temperatures:
- Higher than 100.4 F in infants younger than 3 months
- Higher than 102.2 F in children aged 3 months to 3 years
- Higher than 104 F if you are older than 3 years
- Below 95 F in anyone aged 3 or older