May also be called: Syncope; Swooning; Passing Out

Fainting is a temporary loss of consciousness. It happens when not enough blood reaches the brain due to a fall in blood pressure. It's not a sign of a serious problem.

What Causes Fainting?

Common causes include dehydration, a quick change in position, standing or sitting still for a long period, overheating, hyperventilation (overbreathing), low blood sugar, anemia, some heart problems, and a sudden fear of something (like the sight of blood).

Most fainting spells have warning signs (such as a change in vision, dizziness, nausea, or stomach pain) that happen a few seconds before someone passes out.

Can Fainting Be Prevented?

When warning signs of fainting happen, quickly sitting down, dropping the head between the knees, or lying down on the floor may help someone avoid a loss of consciousness. Then, they should slowly get up after the dizzy feeling has passed.

What Else Should I Know?

Fainting in children, especially teens, is common but shouldn't be ignored. Discuss it with your doctor, especially if it happens during exertion (exercising, running, etc.) or happens often.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.