When Is Fainting a Sign of Danger?

By Temma Ehrenfeld  @temmaehrenfeld
March 16, 2017

Five percent of people who go to an ER after fainting have a serious problem that isn’t obvious. How do you know when fainting means you need immediate care?

Did you know that up to half of all people faint at some point? Fainting usually is caused by low blood pressure.

Nearly always the cause is harmless. Some people faint at the sight of blood, or when their blood is drawn. You might faint when you stand still for long stretches, become dehydrated, or are stuck in a hot stuffy room. Some people faint from emotional shocks.

If you’re bleeding profusely or have other symptoms, go to an ER immediately, even if it seems too inconvenient. You may have a fatal problem.


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About 5 percent of all people who come to an ER because they’ve fainted have a serious problem that isn’t obvious. You might feel fine, yet have a silent heart condition present from birth — and doctors will need to puzzle the situation out with various tests.

So how do you know when a fainting spell means you need immediate care?    

If it’s the first time you’ve fainted, and you also have another symptom — a headache, chest pain, or abdominal pain — call 911 and get to an emergency room immediately, advises Venkatesh Thiruganasambandamoorthy, an ER doctor at the Ottawa Hospital in Ontario. Do the same if you faint while exercising. You may be having a heart attack or another heart issue.

If you have no other symptoms and think you know the trigger, perhaps a shock, you don’t need to rush to the hospital. Just to be sure, get an electrocardiogram (EKG) soon after. The test takes minutes: a technician applies a gel and small patches to your chest, arms, and legs, to record your heart’s electrical activity. An abnormal EKG does not mean you have a serious heart problem, but will alert your doctor to test further.

Don’t worry if your doctor or an ER physician doesn’t offer you an echocardiogram, using ultrasound. An echocardiogram is recommended only if you are older than 59 years, or have an abnormal EKG or other signs of heart disease, according to research published in 2016 in the American Journal of Emergency Medicine. Even an abnormality that shows up on an echocardiogram may be unrelated to your fainting spell: As many as of 25 percent of the population may have them.  

If you faint repeatedly in the same circumstances and don’t have other symptoms, you don’t even need to go to a doctor — but be diligent about avoiding more fainting episodes. You could injure yourself in a fall. Don’t ignore the symptoms when the feeling of fainting comes on, drink enough water, and sit down when you need to.

If you know that injections or blood drawing makes you feel faint, warn the medical personnel, who will make sure you’re lying down.

If the episodes become more common, go to an ER and have an EKG, again for signs that you’ve developed a life-threatening arrhythmia. The ER doctors will also check your blood pressure and take blood tests to look for signs of a heart attack.

Up to nearly 70 percent of elderly people in nursing homes faint just from standing up, according to some estimates. “Orthostatic hypotension,” when your blood pressure can’t adapt quickly enough to the change, can have any number of causes, including dehydration and medications for high blood pressure. It can also be a complication of diabetes or Parkinson’s disease. Although there are medications available to treat this problem, it’s important to try other remedies as well: patients may do better if they drink more or eat more salt, lie in a bed with the head raised, wear a binder around the abdomen, or drink cold water before standing.


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March 03, 2020

Reviewed By:  

Janet O’Dell, RN