There are common infections that can cause fevers and chills, as well as side effects from medications, reactions to exercise, hypothyroidism (underactive thryroid), hypoglycemia (low blood sugar), malnutrition (a lack of nutrients), or frisson (a brief thrill). Chills can last a few hours to a few days.
Exposure to Cold
When you get chills without a fever, such as from exposure to cold environments, your brain sends signals to your body to involuntarily move (shake, chatter, tremble) to produce more heat. These chills typically resolve when your body temperature returns to normal.
You can prevent these chills by dressing for the weather, when possible, by:
Wearing layersChoosing well-insulated but breathable fabricsWearing warm and water-resistant footwear
If you’re experiencing chills at home on a cold day, you can always add layers (sweaters, thicker socks) and get under some blankets with a cup of tea to warm up.
Fever
You can break into a fever after experiencing chills or at the start of an infection. If the fever is mild, 102 F (38.8 C) or less, you can manage it at home by drinking fluids (hydrating and flushing infection) and resting.
Common infections that can cause fever and chills include:
Gastroenteritis (the stomach flu): Digestive tract inflammation and infectious diarrhea commonly caused by viruses (norovirus in adults and rotavirus in children) Influenza: Infections from viruses like influenza A and influenza B Sinusitis: A sinus infection, in which the sinuses fill with fluid caused by viruses (less often bacteria) Pneumonia: A lung infection caused by many different viruses and bacteria, especially Streptococcus pneumoniae (pneumococcus), and fungi Strep throat: A throat infection caused by bacteria known as Group A Streptococcus Complicated urinary tract infection: For example, pyelonephritis, a relatively uncommon infection that causes inflammation in the urethra, kidneys, and bladder due to bacteria Malaria: A life-threatening infection with cold (chills, shivering) and hot stages (fever) caused by a parasite that is rarely seen in the United States
Side Effects of Medication
Some chills are the result of the body’s response to taking medications and adjusting or stopping medications:
Diabetes medications: Insulin and drugs like sulfonylureas and meglitinides that increase insulin secretion by the pancreas can cause hypoglycemia-related chills. This happens if you have too much insulin and haven’t matched it with your food intake or physical activity level. General anesthesia for surgery: People can experience chills upon waking from anesthesia. Chemotherapy medications: Medications that you are taking to calm down your immune system (immunotherapy) and chemotherapy to fight cancer can have flu-like side effects, including fever and chills. Symptoms typically peak and resolve after treatment over a few days.
Reaction to Exercise
There’s a reason it’s called warming up and cooling down. When you exercise, your blood circulates to the muscles and skin, raising your temperature. If you stop the physical activity abruptly, your body can experience temperature shock.
Your internal temperature will drop without gradual adjustments, and you may experience chills as a way of warming up to your average temperature again.
Preventing this unpleasant transition means planning a short cool down period to help your body’s temperature adjust to different levels of physical activity.
Hypothyroidism
Hypothyroidism, or underactive thyroid, can result in a low body temperature as a result of insufficient levels of thyroid hormone. A lack of these hormones causes your metabolism to slow. Hypothyroidism causes intolerance to the cold, so you’re more likely to experience chills if you have this condition.
Hypothyroidism risk factors or causes include:
Thyroiditis (thyroid inflammation)Hyperthyroidism (overactive thyroid) treatment, such as radiation or surgical removalIodine deficiency (the thyroid uses iodine to make hormones)A family history of thyroid problemsBeing female and over age 60 (or after menopause)Postpartum (after giving birth)
Hypothyroidism can be treated with thyroid hormone–stimulating medication. L-thyroxine (levothyroxine) is a commonly used medication.
Hypoglycemia
Chills occur in the mild and moderate stages of hypoglycemia. Hypoglycemia is a condition in which your blood glucose (sugar) is lower than normal, usually under 70 milligrams per deciliter (mg/dL). It can occur in people with diabetes when they continue to take their usual doses of insulin, sulfonylureas, or meglitinides, and they are:
Not eating enough carbohydratesSkipping meals or not eating frequently enoughIncreasing physical activityConsuming too much alcohol without eating enoughSick with the flu or other illnesses
Nondiabetic hypoglycemia is also possible, but it’s much less common.
Having nightmares Sweating through your pajamas or beddingBeing tired, irritable, or confused upon waking
Treatment of quick-onset hypoglycemia includes raising your blood sugar by consuming glucose (carbohydrates). Frequent episodes should be discussed with a healthcare provider or diabetes specialist.
Malnutrition
Feeling cold all the time or most of the time is a symptom of malnutrition. Malnutrition is when your body is starving for nutrients and cannot function properly. Research suggests that even the lack of one vitamin can lead to malnutrition.
Malnutrition has many causes, including:
Not consuming enough nutrientsNot consuming enough foodNot absorbing the nutrients from food
Without the necessary nutrients it needs, your body cannot maintain a healthy and comfortable body temperature, so you’ll experience chills.
If you or a loved one have chills from malnutrition, seek medical attention. Discussing your condition with your healthcare provider, crisis counselor, or a mental health professional may be necessary.
Frisson
Frisson, also known as musical chills or aesthetic chills, is the sensation we tend to call shivering or having goosebumps when experiencing a thrill. Its reaction is similar to that of being cold but without having any exposure to a physical trigger.
Frisson is a short-term, common reaction, and there are many ways of describing the physical response, including:
Shoulders shuddering or raising to your neckTingly feeling down your shoulders and armsLittle hairs standing on endTrickle down your spine
Summary
Chills could be a result of something benign like experiencing the cold or after exercising, or it could be due to an underlying condition. If you have chills for no obvious reason, check with your healthcare provider to make sure your chills are not caused by an urgent medical issue.
Certain musical melodies, especially with sudden changes in volume or voiceCertain buzzing of bugs, such as a mosquito, bee, or fly, especially buzzing near the ear or neck
A Word From Verywell
With so many reasons why you could be experiencing chills, it’s always good to make note of when you have them in case you need to discuss your condition with a medical professional. While the odd frisson here and there is nothing to think twice about, if you are experiencing chills for unknown reasons or after starting a new drug or taking an ongoing medication, talk to your healthcare provider. A practitioner can rule out or diagnose underlying thyroid problems, such as hypothyroidism, or blood sugar problems that can be managed.
If you’re experiencing chills from a fever, try narrowing down the exact cause since different infections, ranging from those caused by viruses or bacteria or parasites, are treated with different medications. If your fever isn’t improving with medication, rest, and plenty of fluids or if you have a very high fever, call your healthcare provider.
