Syncope
Key points
- Fainting is a temporary loss of consciousness due to a drop in blood flow to the brain.
- When you faint, you not only experience loss of consciousness, but also loss of muscle tone and paleness in your face.
- 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.
- If you have a history of fainting and have been evaluated medically, follow your doctor's instructions for how to prevent fainting episodes.
Alternative names
Passed out; Lightheadedness - fainting; Fainting; Vasovagal
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.
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.
Common 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.
Home Care
If you have a history of fainting and have been evaluated medically, follow your doctor's instructions for how to prevent fainting episodes. For example, if you know the situations that cause you to faint, these should be avoided or changed. Avoid sudden changes in posture. Get up from a lying or seated position slowly and gradually. When having blood drawn (if this makes you faint), tell the technician and make sure that you are lying down.
Immediate treatment for fainting includes:
- Check the person's airway and breathing. If necessary, call 911 and begin rescue breathing and CPR.
- Loosen tight clothing around the neck.
- Keep the affected person lying down for at least 10 to 15 minutes, preferably in a cool and quiet space. If the person cannot lie down, have him sit forward and lower his head below the levels of the shoulders, between the knees.
Written and revised by
Gerald Hurowitz, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.