Fainting

Definition

Fainting is a temporary loss of consciousness due to a drop in blood flow to the brain. The episode is brief (lasting less than a couple of minutes) and is followed by rapid and complete recovery. You may feel lightheaded or dizzy before fainting.

A longer, deeper state of unconsciousness is often called a coma.

Alternative Names

Considerations

When you faint, you not only experience loss of consciousness, but also loss of muscle tone and paleness in your face. You may also feel weak or nauseated just prior to fainting and have the sense that surrounding noises are fading into the background.

Causes

Fainting may occur while you are urinating, having a bowel movement (especially if straining), coughing strenuously, or when you have been standing in one place too long. Fainting can also be related to fear, severe pain, or emotional distress.

A sudden drop in blood pressure can cause you to faint. This may happen if you are bleeding or severely dehydrated. It can also happen if you stand up very suddenly from a lying down position.

Certain medications can lead to fainting because of a drop in your blood pressure or other reason. Common drugs that contribute to fainting include those for anxiety, high blood pressure, nasal congestion, and allergies.

Other reasons you may faint include hyperventilation, use of alcohol or drugs, or low blood sugar.

Less common but more serious reasons include heart disease (like abnormal heart rhythm or heart attack) and stroke.