Fainting: Frightening, but seldom serious

Learn why fainting occurs and when you should seek medical attention.

Published: July, 2017

One minute you're feeling a bit woozy; the next thing you know, you're flat on your back wondering what happened. No matter what you call it — swooning, passing out, or fainting — the experience is surprisingly common. About a third of people say they've fainted at least once.

Defined as a sudden, temporary loss of consciousness, fainting occurs when something interrupts blood flow to the brain. Doctors call it syncope, which comes from a Greek word meaning "contraction" or "cut off." Although often harmless, fainting can cause injuries and sometimes signals a problem with the heart or circulatory system.

To continue reading this article, you must log in.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »