Harvard Health Letter

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.

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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.

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