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. The medical name for fainting is syncope.
Passed out; Light-headedness - fainting; Syncope; Vasovagal episode
When you faint, you not only lose consciousness, you also lose muscle tone and the color in your face. Before fainting, you may also feel weak, nauseated, and have the sense that your vision is constricting (tunnel vision) or noises are fading into the background.
Fainting may occur while or after 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 medicines, 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.
If you have a history of fainting, follow your doctor's instructions for how to prevent fainting. 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 to 15 minutes, preferably in a cool and quiet space. If this is not possible, sit the person forward with the head between the knees.
When to Contact a Medical Professional
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 is 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 Office Visit
Your health care provider will ask you questions to determine whether you simply fainted, or if something else happened (such as 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.
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 while you are in several different positions. People with a suspected arrhythmia may need to be admitted to a hospital for testing.
Tests that may be ordered include:
Goldman L. Approach to the patient with possible cardiovascular disease. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, Pa.: Elsevier Saunders; 2011:chap 83.
Olgin JE. Approach to the patient with suspected arrhythmia. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, Pa.: Elsevier Saunders; 2011:chap 62.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.
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