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Fainting

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Desiree got out of the whirlpool at the gym and was on her way to the showers when she felt incredibly dizzy. Next thing she knew, she woke up on the locker room floor with her sister looking over her anxiously. She was pretty scared — what happened?

Desiree's sister thought she'd probably fainted. Although Desiree felt like she'd been unconscious for hours, her sister said she was out for less than a minute. Since Desiree felt fine and she'd never fainted before, she decided she didn't need to go to the ER.

When Desiree asked her school nurse about it the next day, she said Desiree probably fainted because she stayed in the whirlpool too long or the temperature was set too high, affecting her body temperature.

Why Do People Faint?

Fainting is pretty common in teens. The good news is that most of the time it's not a sign of something serious.

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When someone faints, it's usually because changes in the nervous system and circulatory system cause a temporary drop in the amount of blood reaching the brain. When the blood supply to the brain is decreased, a person loses consciousness and falls over. After lying down, a person's head is at the same level as the heart, which helps restore blood flow to the brain. So the person usually recovers after a minute or two.

Reasons Why You Might Swoon

Here are some of the reasons why teens faint:

  • Physical triggers. Getting too hot or being in a crowded, poorly ventilated setting are common causes of fainting in teens. People can also faint after exercising too much or working out in excessive heat and not drinking enough fluids (so the body becomes dehydrated). Fainting can also be triggered by other causes of dehydration, as well as hunger or exhaustion. Sometimes just standing for a very long time or getting up too quickly after sitting or lying down can lead someone to faint.
  • Emotional stress. Emotions like fright, pain, anxiety, or shock can affect the body's nervous system, causing blood pressure to drop. This is the reason why people faint when something frightens or horrifies them, like the sight of blood.
  • Hyperventilation. A person who is hyperventilating is taking fast breaths, which causes carbon dioxide (CO2) to decrease in the blood. This can make a person faint. People who are extremely stressed out, in shock, or have certain anxiety disorders may faint as a result of hyperventilation.
  • Drug use. Some illegal drugs — such as cocaine or methamphetamine — can cause fainting (and even a heart attack in some cases). Inhalant use ("huffing") can lead to fainting by causing problems with a person's heartbeat. Fainting is also a side effect of some prescription medications.
  • Low blood sugar. The brain depends on a constant supply of sugar from the blood to work properly and keep a person awake. People who are taking insulin shots or other medications for diabetes can develop low blood sugar and pass out if they take too much medicine or don't eat enough. Sometimes people without diabetes who are starving themselves (as with crash dieting) can drop their blood sugar low enough to faint.
  • Anemia. A person with anemia has fewer red blood cells than normal, which decreases the amount of oxygen delivered to the brain and other tissues. Girls who have heavy periods or people with iron-deficiency anemia for other reasons (like not getting enough iron in their diet) may be more likely to faint.
  • Pregnancy. During pregnancy the body normally undergoes a lot of changes, including changes in the circulatory system, which can cause a woman to faint. In addition, the body's fluid requirements are increased, so pregnant women may faint if they aren't drinking enough. And as the uterus grows it can press on and partially block blood flow through large blood vessels, which can decrease blood supply to the brain.
  • Eating disorders. People with anorexia or bulimia may faint for a number of reasons, including dehydration, low blood sugar, and changes in blood pressure or circulation caused by starvation, vomiting, or overexercising.
  • Cardiac problems. An abnormal heartbeat and other heart problems can cause a person to faint. If someone is fainting a lot, especially during exercise or exertion, doctors may suspect heart problems and run tests to look for a heart condition.

Some medical conditions — like seizures or a rare type of migraine headache — can cause people to seem like they are fainting. But they're not the same thing as fainting and are handled differently.

Can You Prevent Fainting?

Bagging Hyperventilation

Some people feel dizzy immediately before they faint. They may also notice changes in vision (such as tunnel vision), a faster heartbeat, sweating, and nausea. Someone who is about to faint may even throw up.

If you think you're going to faint, you may be able to head it off by taking these steps:

  • If possible, lie down. This can help prevent a fainting episode as it allows blood to circulate to the brain. Just be sure to stand up again slowly when you feel better — move to a sitting position for several minutes first, then to standing.
  • Sit down with your head lowered forward between your knees. This will also help blood circulate to the brain, although it's not as good as lying down. When you feel better, move slowly into an upright seated position, then stand.
  • Don't let yourself get dehydrated. Drink enough fluids, especially when your body is losing more water due to sweating or being in a hot environment. Drink enough fluids before and during sports and exercise.
  • Keep blood circulating. If you have to stand or sit for a long time, periodically tense your leg muscles or cross your legs to help improve blood return to the heart and brain. And try to avoid overheated, cramped, or stuffy environments.

What Should You Do?

If you've only fainted once, it was brief, and the reasons why are obvious (like being in a hot, crowded setting), then there's usually no need to worry about it. But if you have a medical condition or are taking prescription medications, it's a good idea to call your doctor. You should also let your doctor know if you hurt yourself when you fainted (for example, if you banged your head really hard).

If you also have chest pain, palpitations (heart beating fast for no reason), shortness of breath, or seizures, or the fainting occurred during exercise or exertion, talk with your doctor — especially if you've fainted more than once. Frequent fainting may be a sign of a health condition, like a heart problem.

What Do Doctors Do?

For most teens, fainting is not connected with other health problems, so a doctor will probably not need to do anything beyond examining you and asking a few questions.

If concerned about your fainting, the doctor may order some tests in addition to giving you a physical exam and taking your medical history. Tests depend on what the doctor thinks might be causing the problem. Common tests include an EKG (a type of test for heart problems), a blood sugar test, and sometimes a blood test to make sure a person is not anemic.EKG Video Image

If test results show that fainting is a symptom of another problem, such as anemia, the doctor will advise you on treatments for that problem.

Helping Someone Who Faints

If you're with someone who has fainted, try to make sure the person is lying flat, but avoid moving the person if you think he or she might have been injured when falling (moving an injured person can make things worse).

Instead, loosen any tight clothing — such as belts, collars, or ties — to help restore blood flow. Propping the person's feet and lower legs up on a backpack or jacket can also help move blood back toward the brain.

Someone who has fainted will usually recover quickly. Because it's normal to feel a bit weak after fainting, be sure the person stays lying down. Getting up too quickly may bring on another fainting spell.

Call 911 if someone who has fainted does not regain consciousness after about a minute or is having difficulty breathing.

Reviewed by: Yamini Durani, MD
Date reviewed: September 2010

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Note: All information is for educational purposes only. For specific medical advice, diagnoses and treatment, consult your doctor.

© 1995–2014 The Nemours Foundation/KidsHealth. All rights reserved.

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