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Alternate Names

  • rigors
  • shivering


A chill is a sensation of cold, sometimes associated with a shiver. When chills occur at an unexpected time, they may represent fever due to an illness.

What is going on in the body?

Anyone can experience chills as a normal reaction, such as going out into the cold. In medical terms, chills usually refer to those that occur in an unexpected setting. The brain closely regulates the body's normal temperature. When an infection occurs, infection-fighting cells in the body make certain chemicals.
In some cases, these chemicals may travel through the bloodstream and cause the brain to raise the normal temperature set point inside the body. When this occurs, a person gets a feeling of cold..
Shivering may even occur, as the body tries to use muscle movement to raise the temperature. When the new set point is reached, the feeling stops, and if the temperature is measured at this point, it will show that the person has a fever.
When the fever-causing chemicals are no longer being produced, the exact opposite happens. The brain lowers the temperature set point, and the body brings the temperature down to normal by sweating. Some illnesses are marked by several cycles of chills and sweats.


What are the causes and risks of the condition?

Chills have several causes, including:
  • menopause, which can cause chills as well as hot flashes and other symptoms
  • infections of any type, especially when bacteria get into the bloodstream. Common infections that cause chills include flu, strep throat, and pneumonia.
  • cancers of the blood and lymph cells (leukemias and lymphomas)
  • reactions to medications, such as antibiotics and anti-seizure medications
  • autoimmune disorders, in which a person's immune system attacks his or her own body.
An example is systemic lupus erythematosus (SLE), which can affect many areas of the body.
In some cases, the cause is unknown. Many elderly people feel cold at temperatures that younger people find normal. This is generally considered a normal effect of aging.


What can be done to prevent the condition?

Prevention of chills is related to the cause, but is often not possible. Avoiding sick people and medications that can cause chills may help prevent some cases.


How is the condition diagnosed?

In some cases, the reason for chills is obvious from the history and physical exam. In other cases, further tests are ordered. A complete blood count (CBC) can help diagnose an infection or blood cancer. Blood hormone levels may be measured if menopause is suspected.
If an autoimmune disorder is suspected, an antibody titer may be done. If a kidney infection is suspected, a urinalysis and urine culture may be done on a sample of urine. Other tests may also be ordered in certain settings. For instance, a chest x-ray will usually show a pneumonia if it is present.

Long Term Effects

What are the long-term effects of the condition?

Chills themselves are temporary, and cause no long-term effects. Long-term effects are entirely related to the cause. For instance, those with the flu often get better and have no long-term effects.
Pneumonia may be cured with antibiotic treatment, but can cause death in severe cases. Autoimmune disorders can cause damage to different areas of the body, such as the kidney, joints, and lungs.

Other Risks

What are the risks to others?

Chills are not contagious. However, if the chills are due to an infection, the infection may be contagious.


What are the treatments for the condition?

Treatment for chills is directed at the cause. Acetaminophen or ibuprofen can be used to reduce a person's fever. If a person has an infection, antibiotics may be advised. If a medication is the cause, it may need to be stopped.
Women going through menopause may want to discuss hormone therapy options with a healthcare professional. Medications can replace the main female hormones, such as estrogen, that become low in menopause.
A person with an autoimmune disorder may need medications to reduce inflammation or suppress the immune system. Someone with cancer may need surgery, chemotherapy, or radiation treatment.

Side Effects

What are the side effects of the treatments?

Side effects depend on the treatments used. For instance, ibuprofen (i.e., Advil, Motrin) can cause allergic reactions and stomach upset. Prednisone can cause weight gain, weakened bones, and mood swings. Hormone therapy has many side effects, such as an increased risk of blood clots. Surgery can be complicated by infection, bleeding, or a reaction to the anesthetic.

After Treatment

What happens after treatment for the condition?

Someone with the flu often gets better in a few days with or without treatment. A person with cancer or an autoimmune disorder may need treatment for life.


How is the condition monitored?

Any new or worsening symptoms should be reported to the healthcare professional. Other monitoring will depend on the cause. For instance, those with cancer of the blood or lymph cells may need repeated blood tests, and possibly bone marrow biopsies, to follow the disease and the response to treatment.


Harrison's Principles of Internal Medicine, 1998, Fauci et al.

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