Causes of Fainting

Fainting occurs due to a sudden drop in blood flow to the brain, resulting in brief loss of consciousness. Fainting can be accompanied by dizziness or nausea.

Here are some common triggers, courtesy of the U.S. National Library of Medicine:

• Straining during urination or a bowel movement.

• Excessive coughing.

• Standing for too long in the same position, or quickly standing up from a lying position.

• Severe pain, stress, fear or emotional distress.

• Excessive bleeding or dehydration.

• Medications used to treat conditions like high blood pressure, anxiety, allergies and nasal congestion.

• Use of drugs or alcohol.

• Low blood sugar.

If you see someone faint, the U.S. National Library of Medicine recommends that you:

• Check to be sure the person is still breathing, is not injured or bleeding, and has regained consciousness quickly. If not, call 911 immediately.

• Loosen clothing around the person's neck.

• Have the person lie down in a cool, quiet place for at least 10 to 15 minutes after regaining consciousness, or if he can't lie down, have him sit with his head below the shoulders, between his knees.

• Prop up the person's feet about a foot above the level of the heart.

• If the person has vomited, turn him on his side to prevent choking.