Fainting is a brief loss of consciousness due to a drop in blood flow to the brain. The episode lasts less than a couple of minutes and you recover from it quickly and completely. You may feel light-headed or dizzy before fainting.
A longer, deeper state of unconsciousness is often called a coma.
Passed out; Light-headedness – fainting; Syncope; Vasovagal episode
When you faint, you not only lose consciousness, but you also lose muscle tone and the color in your face (pallor). You may also feel weak or nauseated just before fainting. You may have the sense that noises are fading into the background.
Fainting may occur while you:
- Cough very hard
- Have a bowel movement (especially if you are straining)
- Have been standing in one place for too long
Fainting can also be related to:
- Emotional distress
- Severe pain
Other causes of fainting:
- Certain medications, including those used for anxiety, depression, high blood pressure, and allergies (these drugs may cause a drop in blood pressure)
- Drug or alcohol use
- Low blood sugar
- Sudden drop in blood pressure (such as from bleeding or being severely dehydrated)
- Standing up very suddenly from a lying position
Less common but more serious reasons for fainting include heart disease (such as abnormal heart rhythm or heart attack) and stroke. These conditions are more likely in persons over age 65 and less likely in those younger than 40.
If you have a history of fainting, follow your doctor’s instructions for how to prevent fainting episodes. For example, if you know the situations that cause you to faint, avoid or change them.
Get up from a lying or seated position slowly. If having blood drawn makes you faint, tell your health care provider before having a blood test and make sure that you are lying down when the test is done.
You can take immediate treatment steps when someone has fainted:
- Check the person’s airway and breathing. If necessary, call 911 and begin rescue breathing and CPR.
- Loosen tight clothing around the neck.
- Raise the person’s feet above the level of the heart (about 12 inches).
- If the person has vomited, turn onto his or her side to prevent choking.
- Keep the person lying down for at least 10 – 15 minutes, preferably in a cool and quiet space. If this is not possible, sit the person forward with the head between the knees.
Call your health care provider if
Call 911 if the person who fainted:
- Fell from a height, especially if injured or bleeding
- Does not become alert quickly (within a couple of minutes)
- Is pregnant
- Is over age 50
- Has diabetes (check for medical identification bracelets)
- Feels chest pain, pressure, or discomfort
- Has a pounding or irregular heartbeat
- Has a loss of speech, vision problems, or is unable to move one or more limbs
- Has convulsions, a tongue injury, or a loss of bladder or bowel control
Even if it’s not an emergency situation, you should be seen by a doctor if you have never fainted before, if you faint often, or if you have new symptoms with fainting. Call for an appointment to be seen as soon as possible.
What to expect at your health care provider’s office
Your health care provider will ask you questions to determine whether you simply fainted, or if something else happened (like a seizure or heart rhythm disturbance), and to figure out the cause of the fainting episode. If someone witnessed the fainting episode, their description of the event may be very helpful.
The questions will include:
- Is this the first time you have fainted?
- When did you faint? What were you doing before it occurred? For example, were you going to the bathroom, coughing, or standing for a long time?
- Did fainting occur with exercise?
- How would you describe the dizziness that you felt before fainting? Did you feel light-headed, off-balance, or like the room was spinning?
- Did the faint occur with convulsions (jerking muscle movements), tongue injury, or loss of bowel control?
- When you regained consciousness, were you aware of your surroundings or were you confused?
- Did you experience chest pain or heart palpitations before you fainted?
- Do you faint when you change positions — for example, going from lying to standing?
The physical examination will focus on your heart, lungs, and nervous system. Your blood pressure may be measured in several different positions. People with a suspected arrhythmia may need to be admitted to a hospital for testing.
Tests that may be performed include:
- Blood tests for anemia or body chemical imbalances
- Cardiac rhythm monitoring
- Electrocardiogram (ECG)
- Electroencephalogram (EEG)
- Holter monitor
- X-ray of the chest
Calkins H, Zipes DP. Hypotension and syncope. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 42.
Simon RP. Syncope. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 427.