When should you worry about fainting?
Fainting may be caused by something serious, such as a heart problem or a seizure, or by something minor, such as laughing too hard.
Don't try to diagnose yourself; get to a hospital if you lose consciousness, even for a moment.
Fainting can be alarming, and it should be. While often the cause of fainting is something minor, fainting also can be a sign of a serious underlying medical concern. "The problem is that you can't evaluate yourself, and you should let a physician determine if fainting is worrisome or not," says Dr. Shamai Grossman, an associate professor of emergency medicine at Harvard Medical School, who has conducted 20 studies on fainting.