Fainting occurs when your brain temporarily doesn't receive enough blood supply, causing you to lose consciousness. This loss of consciousness is usually brief.

Fainting might have no medical significance. Or the cause can be a serious disorder, often involving the heart. Therefore, treat loss of consciousness as a medical emergency until the signs and symptoms are relieved, and the cause is known. Talk to your doctor if you faint more than once.

If you feel faint

• Lie down or sit down. To reduce the chance of fainting again, don't get up too quickly.
• Place your head between your knees if you sit down.

If someone else faints

• Position the person on his or her back. If there are no injuries and the person is breathing, raise the person's legs above heart level — about 12 inches (30 centimeters) — if possible. Loosen belts, collars or other constrictive clothing.

  To reduce the chance of fainting again, don't get the person up too quickly. If the person doesn't regain consciousness within one minute, call 911 or your local emergency number.

• Check for breathing. If the person isn't breathing, begin CPR. Call 911 or your local emergency number. Continue CPR until help arrives or the person begins to breathe.

If the person was injured in a fall associated with a faint, treat bumps, bruises or cuts appropriately. Control bleeding with direct pressure.