Causes

Hot flashes are most commonly caused by changing hormone levels before, during and after menopause. It's not clear exactly how hormonal changes cause hot flashes. But most research suggests that hot flashes occur when decreased estrogen levels cause your body's thermostat (hypothalamus) to become more sensitive to slight changes in body temperature. When the hypothalamus thinks your body is too warm, it starts a chain of events — a hot flash — to cool you down.

Rarely, hot flashes and nights sweats are caused by something other than menopause. Other potential causes include medication side effects, problems with your thyroid, certain cancers and side effects of cancer treatment.