Should You Go To The Doctor After Fainting? Here's How To Tell.

Not every fainting spell requires a trip to the emergency room.
How to tell whether you should go to the doctor after a fainting spell.
Eric O'Connell via Getty Images
How to tell whether you should go to the doctor after a fainting spell.

Summer’s in full swing, and the hot, sweltering days might make some people more prone to fainting.

Fainting, also known by the medical term syncope, is a momentary loss of consciousness caused by lack of blood flow to the brain. It can strike anyone, and it’s fairly common. Researchers estimate that anywhere between 15 and 39 percent of people will experience fainting at least once in their life, but people who take certain medications may be more prone to feeling dizzy, weak and eventually passing out. Still others may be more prone to fainting for genetic reasons.

Syncope can be caused by a wide variety of different conditions, but generally resolves on its own with no harm to the person who fainted. Read on for five common reasons we faint, what we should do if it happens to us or someone nearby, and the warning signs for more serious conditions.

You may have fainted because...

1. You’re dehydrated

Because fainting is caused by a lack of blood flow to the brain, dehydration can up your risk for fainting. It decreases blood volume, which in turn lowers blood pressure. To avoid dehydration in the summer time, drink lots of water and pace yourself if you’re drinking alcohol. Booze further dehydrates your body, which is why large amounts of alcohol and sun are a recipe for fainting.

2. You’ve been standing for a long time

Every wedding season, a few news stories surface of a bridesmaid so overwhelmed by the ceremony that she faints at a crucial moment. While they may be dehydrated (or truly verklempt), the fact that bridesmaids stand still for so long ups the faint factor. The same thing appeared to happen to a hapless British soldier who fainted during a ceremony to celebrate the queen’s birthday this year.

A soldier collapses on Horse Guards Parade ahead of the Queen's Birthday Parade, 'Trooping the Colour', in London on June 11, 2016.
OLI SCARFF via Getty Images
A soldier collapses on Horse Guards Parade ahead of the Queen's Birthday Parade, 'Trooping the Colour', in London on June 11, 2016.

Standing still for a long time causes blood to pool in the legs and feet, which draws it away from the brain. One way to prevent this, according to Dr. Richard Nicholas of the University of Arkansas for Medical Sciences, is to wiggle your toes, flex your leg muscles and move around slightly when you have to stand for long periods of time.

3. You saw blood (or had a similar emotional trigger)

For some people, seeing something extremely upsetting like blood is enough to trigger a fainting episode. In this case, fainting happens when a phobic shock triggers a clash between the sympathetic nervous system (which is responsible for the body’s fight-or-flight response) and the parasympathetic system (responsible for the body’s rest-and-digest response).

The clash both slows down the heart rate and causes blood vessels to expand, decreasing blood pressure and starving the brain of oxygen. Some researchers believe that fainting at the sight of blood is actually an evolutionary advantage that forced our ancestors to “play dead” during massacres and battles, ensuring their survival.

This same nervous system overreaction is also at play when people faint in extremely emotional or high-anxiety situations. Consider, for instance, the Beatles fans who fainted at the sight of their idols, or the father of four daughters who shook and fainted after learning his wife was pregnant with a boy.

4. You’re exhausted

This is something our founder and editor-in-chief Arianna Huffington is unfortunately all too familiar with. After weeks of running on four to five hours of sleep every night, she fainted from exhaustion in 2007. While most people who faint aren’t harmed from the experience, Huffington was ― she hit her desk on the way down, breaking her cheekbone. The injury required five stitches to repair, and the collapse was a wake up call to change the pace of her life and get more sleep on a regular basis.

5. There’s something seriously wrong

Fainting can also be caused by other medical conditions like seizures, low blood sugar, chronically low blood pressure or heartbeat irregularities. In these cases, fainting ― or an event that looks like fainting ― is just one symptom of a more serious condition that could need diagnosis and treatment.

For instance, some people feel dizzy and faint every time they get up from a seated position. This low blood pressure, which is triggered by standing, is called orthostatic hypotension and may be a sign of a more serious condition that should be treated with medicine.

“That’s an extremely serious problem, not because of the fainting per se, but because it reflects dysfunction of the autonomic nervous system in many other ways,” explains Dr. David Robertson, an expert on the autonomic nervous system and a professor of medicine, pharmacology and neurology at Vanderbilt University Medical Center.

What to do if you see someone faint

Help them lie down on their back, preferably in a cool, shady spot. Prop up their feet slightly to allow any blood that has pooled in the legs to make its way back to the heart and the head, which should revive them promptly. When they awaken, give them some cool water to drink, and eventually see if they can stand and walk on their own.

If they feel absolutely fine and do not have any dizziness, chest pain, belly pain or a headache, there’s probably no cause for concern, experts say.

“If you have a faint and you get them lying down, many people will almost immediately come back to consciousness,” said Robertson.

How do you know if you’re supposed to see a doctor after fainting?

For most cases of syncope, it will be obvious what triggered the fainting spell: heat, dehydration, standing for long periods of time, or the sight of blood.

Still, no matter what the trigger, if it’s the first time someone has fainted, he or she should make an appointment to see their primary care physician within the week to run some tests and make sure there’s nothing more serious that should have caused the syncope, says Dr. Venkatesh Thiruganasambandamoorthy, a scientist and professor at the Ottawa Hospital and the University of Ottawa who specializes in syncope. If tests have ruled out any serious health problems and a person continues to faint occasionally, then fainting prevention becomes all about avoiding triggers, whether they be alcohol use that leads to dehydration, heat or any other identifiable cause.

Thiruganasambandamoorthy recently developed a screening tool for emergency department doctors to see whether patients who have fainted should undergo more extensive tests or be quickly discharged from the emergency room. He hopes to use his research to develop an app for first responders and the general public to determine if a faint should be followed by an ER visit. But for now, he recommends that if anyone has a history of heart disease, heart attacks, irregular heartbeat, clots in the lung, heart valve problems, multiple medical problems or a family history of people dropping dead at a young age, they go to an emergency room after a fainting spell.

Most people who faint do not need to go to the emergency room, but for a small minority of people who do faint, the brief loss of consciousness can be a sign that more serious and potentially fatal medical events are on the horizon. Anywhere from seven to 23 percent of people who show up to the emergency room after a fainting spell will have a serious medical event within seven to 30 days, including heart attack, pulmonary embolism, heart arrhythmia and even death. A doctor will be able to tell if someone is at risk of any serious complications, including what signs to watch out for as they recover at home.

Another sign someone should go to the emergency room or urgent care is a lack of identifiable causes or triggers. For instance, if someone fainted while relaxing in their cool home, free of any emotional or anxious stressors, that is a cause for concern, said Robertson. But these cautions apply in only a minority of cases, he emphasized.

“We don’t want to frighten people to death,” said Robertson. “For most people, a faint is a very simple thing.”

Before You Go

Jump in the pool

Healthy Ways To Cool Down This Summer

Do you have info to share with HuffPost reporters? Here’s how.

Go to Homepage

MORE IN Wellness