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Side Effects

What Are Hot Flashes and Sweating?

In people with cancer, certain conditions and medications can cause sweating, hot flashes, or night sweats. They happen when your body tries to lower its temperature. They can happen even when the area around you or the room you're in is cool.

  • Sweating is also known as perspiring. Sweat, or perspiration, is the fluid created by the sweat glands in the body when heat is given off through skin. 
  • Hot flashes can cause sweating which can range from mild to excessive. Sometimes these are called hot flushes.
  • Night sweats are sweating and hot flashes that mostly happen when you're sleeping .


Sweating is your body's way to lower its temperature. It normally happens when your body is exposed to heat, after exercise, because of hormone changes, or when people are feeling anxious and stressed. If you are sick, having a fever can also cause sweating. In people with cancer, sweating can also be caused by a fever, a tumor, or cancer treatment.

Hot flashes

Hot flashes involve sweating, but can be described as a sensation of heat or flushing. They might include flushing in the face or may be described as heat in other areas of the body. People who have hot flashes describe them as ranging from feeling just a sensation of warmth with mild sweat to having chills and enough perspiration to soak your clothes or bedding. If hot flashes are moderate to severe, sometimes you might have problems sleeping and fatigue, too.

Hot flashes often normally occur in women because of hormone changes during menopause. In women being treated with hormone therapy for breast cancer, hot flashes can have different severity and can be long-lasting.

Hot flashes can also occur in women being treated for other cancers with methods known to have early menopause or temporary hormone changes as a side effect. These hot flashes might be temporary or long-lasting depending on the treatment given.

Men being treated for prostate cancer who have surgery and androgen suppression therapy may have hot flashes for a period of time that might eventually go away. If your treatment plan includes any of these treatments or if you are having hot flashes, talk to your cancer care team so they can assess your specific situation.

What to look for

  • Feeling unusually hot in one or more areas of your body.
  • Having wet or damp skin any time of day, including during the night or waking up to find sheets damp.
  • Fever followed by heavy sweating as the body temperature goes back down
  • Chilling or shaking chills
  • Drenching sweats even when there’s no fever or the area around you doesn't seem overly hot.

    The American Cancer Society medical and editorial content team

    Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

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    Last Revised: December 9, 2020

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