A bout of the chills is usually nothing major to worry about. Here's how to tell if something more serious might be going on.

By Amanda Gardner
March 18, 2019

The most likely explanation for why you have chills is just that—surprise, surprise—you’re cold. When your body temp goes down, your muscles contract and relax as a way to produce heat. (Smart, right?) You may also experience little tremors and goosebumps.

But the same physiological reactions can also be a sign that something is wrong with your health. Usually this is nothing major, but, every once in a while, it can be. Here are a few of the things that can cause chills.

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Emotions

You’ve probably had the experience many times: A piece of beautiful music or a touching story sends a chill down your spine. “The brain and sympathetic nervous system have a lot to do with getting chills,” says Don Middleton, MD, vice president for family practice education at the University of Pittsburgh Medical Center, who says he has personally experienced chills from hearing bagpipes (and even thinking about it). In these cases, the chills are just a sign of a “peak” subjective emotional response, and often a good one, so there’s no need to worry.

Infections

Having the chills is often an early red flag that you’re about to get sick from a virus or bacteria, Dr. Middleton says. “Typically, it’s muscle-shaking triggered by chemicals loosened either from organisms invading the body or from your own protective cells that fight off infection.”

Often the chills come before a fever, giving you the odd sensation of feeling cold even though your body is burning up. Typically, chills come on at the start of an illness, so you can even have chills without fever. “When you get a virus, chills typically come at the beginning, and then you have the fever and feel generally achy,” Dr. Middleton says.

Chills can also appear later, particularly if your viral load surges. If you find that you become significantly more ill—which includes worsening chills—after several days of feeling achy and having other symptoms of a cold, see your doctor.

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Malaria

Chills are a classic symptom of malaria, a parasitic infection transmitted by mosquitoes. A typical malaria attack can include not just chills but also a fever, sweats, headache, body aches, nausea, and vomiting. These attacks recur at different time intervals; some people can go weeks or months without an attack before experiencing the chills again seemingly out of the blue.

In tropical climates, where malaria is common, patients often recognize the symptom quickly. In the U.S. and other places where malaria is less common, it can be mistaken for the flu.

Drug reactions

Some people experience chills and “flu-like syndrome” after taking certain medications. “Chills may be a sign of any serious allergy to drugs, regardless of drug class,” says Dr. Middleton, who is also a professor of family medicine at the University of Pittsburgh School of Medicine. “Antibiotics are frequently at fault. Maddeningly, they are given to individuals who have infections, so sometimes differentiating the chills due to infection from the chills due to a drug reaction is difficult.”

These reactions have also been noted with blood or blood-product transfusions, chemotherapy, and even contrasting agents used for imaging tests. And they can happen when you stop a medication too. “Chills may also accompany drug withdrawal, particularly from agents like narcotics or some antidepressants,” says Dr. Middleton.

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Rheumatoid arthritis

Any disease that involves an increase in white blood cell activity may involve the chills. This includes rheumatoid arthritis, lupus, and gout.

“The breakdown of the white blood cells probably leads to chemicals that cause the chills, probably through triggering the hypothalamus in the brain,” Dr. Middleton explains.

Lyme disease

The classic early symptom of Lyme disease, transmitted through the bite of an infected tick, is the bull’s-eye rash, white in the center and red on the outside—often where the tick bit you. Other symptoms can feel a lot like the flu: chills, fever, headache, feeling sore and tired, and even vomiting. If you notice these symptoms along with the telltale rash, see a doctor quickly. Lyme disease is best treated early.

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Infectious arthritis

Infectious arthritis is joint pain that is caused by infection with a bacterium, virus, or fungi (but most commonly a bacterium), and the chills can be one symptom. Staphylococcus aureus bacteria commonly cause infectious arthritis. Streptococcus and even gonococcus bacteria (the same organisms that causes gonorrhea) can also cause infectious arthritis. Usually, the infection happens somewhere else in your body then travels through the bloodstream to the joints. Once in a while, the infection starts in a joint.

Cancer

Certain types of cancer, namely leukemia and lymphoma, can also cause chills, but they feel different than the chills you might get from a passing infection like a cold.

“Typically for an infection, you have one or two major chills, then a fever, and you feel really bad,” says Dr. Middleton. “If you have cancer, you might get a chill every night. That really means you need to see a physician.”

Get more on infectious diseases here.