What happens when you faint?

Robert H. Shmerling, MD

Senior Faculty Editor, Harvard Health Publishing

About 1 in 3 people report at least one episode of fainting during their lifetime, so it’s surprising that we don’t see people fainting more often. Fainting is usually harmless, the body’s response to emotional or physical stress. But in some cases, fainting can indicate an underlying problem such as heart abnormalities or seizures. And even when the cause of fainting is not that serious, fainting that leads to a fall can cause injury.

Hospitalization after fainting can do more harm than good

Fainting can be alarming. Sometimes it’s a signal of a heart or other problem that needs to be fixed. But sometimes it is nothing to worry about, caused by not eating, having blood drawn, or even laughing too hard. Up to one-third of people at low risk for serious short-term problems after fainting end up being hospitalized. A research letter in this week’s JAMA Internal Medicine points out that hospitalization for low-risk fainting can do more harm than good. Just because you’re in the emergency department after fainting doesn’t mean you need to be admitted to the hospital. Ask your physician if you’re at risk for a worse event if you go home, and make sure that if you’re admitted it’s because there’s a potential serious cause for your fainting that can’t be fully assessed in the emergency department.