Syncope means fainting or passing out. When fainting is caused by certain triggers, like the sight of blood or a needle, or an intense emotion like fear or fright, it’s called vasovagal syncope. It’s the most common cause of fainting.

Vasovagal syncope is sometimes referred to as a neurocardiogenic or reflex syncope.

Anyone can experience vasovagal syncope, but it tends to be more common in children and young adults. This type of fainting happens to men and women in equal numbers.

Although some causes of fainting can be a sign of a more serious health problem, that’s typically not the case with vasovagal syncope.

This article will cover the causes, diagnosis, and treatment for vasovagal syncope, as well as signs that you should see a doctor.

There are special nerves throughout your body that help control how fast your heart beats. They also work to regulate your blood pressure by controlling the width of your blood vessels.

Usually, these nerves work together to ensure that your brain is always getting enough oxygen-rich blood.

But, sometimes, they can get their signals mixed up, especially when you have a reaction to something that causes your blood vessels to suddenly open wide and your blood pressure to drop.

The combination of a drop in blood pressure and a slower heart rate can reduce the amount of blood flowing to your brain. This is what causes you to pass out.

Besides reacting to the sight of something that scares you, or a having an intense emotional reaction, some other triggers that can cause a vasovagal syncope include:

  • standing after sitting, bending, or lying down
  • standing for a long time
  • getting overheated
  • intense physical activity
  • severe pain
  • intense coughing


Vasovagal syncope is caused by a sudden drop in blood pressure, often triggered by a reaction to something. This causes your heart to slow down for a short time. As a result, your brain may not get enough oxygen-rich blood, which causes you to pass out.

Vasovagal syncope is typically not a serious health condition.

Was this helpful?

You might not have any indication that you’re going to faint until it happens. But some people do have brief signs that signal they may be about to faint. These include:

If you typically experience these warning signs before fainting, it’s a good idea to lie down to help increase the blood flow to your brain. This may prevent you from fainting.

If you do pass out, you’ll likely regain consciousness within a few moments, but you might feel:

  • exhausted
  • nauseated
  • lightheaded

You may even feel a little confused or just plain “out of it” for a few minutes.

If you’ve seen a doctor before and know you have vasovagal syncope, you don’t have to go back every time you faint.

You certainly should keep your doctor in the loop, though, if you develop new symptoms or if you’re having more fainting episodes even though you’ve eliminated some of your triggers.

If you’ve never fainted before, and suddenly have a fainting episode, be sure to get medical attention. Some conditions that may make you prone to fainting are:

Fainting can also be a side effect of medications, particularly antidepressants and drugs that affect blood pressure. If you think that’s the case, don’t stop taking your medication without talking to your doctor about alternatives.

If your doctor thinks your medications may be causing you to faint, they’ll work with you to figure out how to safely taper you off of them without causing other side effects.

Seek emergency medical attention if you (or someone else) lose consciousness and:

  • fall from a great height, or injure your head when fainting
  • it takes more than a minute to regain consciousness
  • have trouble breathing
  • have chest pain or pressure
  • have trouble with speech, hearing, or vision
  • loose bladder or bowel control
  • appear to have had a seizure
  • are pregnant
  • feel confused hours after fainting

Your doctor or healthcare provider will start with a detailed medical history and a general physical examination. This exam will likely include several blood pressure readings taken while you’re sitting, lying down, and standing.

Diagnostic testing might also include an electrocardiogram (ECG or EKG) to evaluate your heart rhythm.

That may be all it takes to diagnose vasovagal syncope, but your doctor may want to rule out some other possible causes. Depending on your specific symptoms and medical history, further diagnostic testing may include:

  • Tilt-table test. This test allows your doctor to check your heart rate and blood pressure when you’re in different positions.
  • Portable Holter monitor. This is a device you wear that allows for detailed 24-hour heart rhythm analysis.
  • Echocardiogram. This test uses sound waves to produce images of your heart and its blood flow.
  • Exercise stress test. This test usually involves walking briskly or running on a treadmill to see how your heart functions during physical activity.

These tests can help confirm that you have vasovagal syncope or point to another diagnosis.

Vasovagal syncope doesn’t necessarily call for treatment. But it’s a good idea to try avoid those situations that trigger fainting and take measures to prevent injury due to falling.

There is no standard treatment that can cure all causes and types of vasovagal syncope. Treatment is individualized based on the cause of your recurrent symptoms. Some clinical trials for vasovagal syncope have yielded disappointing results.

If frequent fainting is affecting your quality of life, talk to your doctor. By working together, you may be able to find a treatment that helps.

Some of the medications used to treat vasovagal syncope include:

Your doctor will make a recommendation based on your medical history, age, and overall health. In the most severe cases, your doctor might want to discuss the pros and cons of getting a pacemaker.

It may not be possible to completely prevent vasovagal syncope, but you may be able to cut down on how often you faint.

The most important step is to try and determine your triggers.

Do you tend to faint when you have your blood drawn, or when you watch scary movies? Or have you noticed that you feel faint when you’re overly anxious, or have been standing for a long time?

If you’re able to find a pattern, try to take steps to avoid or work around your triggers.

When you start to feel faint, immediately lie down or sit in a safe spot if you can. It could help you avoid fainting, or at least prevent injury due to a fall.

Vasovagal syncope is the most common cause of fainting. It’s typically not connected to a serious health problem, but it’s important to see a doctor who can rule out any underlying conditions that could be causing you to faint.

This type of fainting episode is usually caused by certain triggers, like the sight of something that scares you, an intense emotion, getting overheated, or standing for too long.

By learning to identify your triggers, you might be able to minimize fainting spells and avoid hurting yourself if you do lose consciousness.

Because fainting can have other causes, it’s important to see your doctor if you suddenly have a fainting episode, or haven’t had one before.

Get immediate medical care if you injure your head when you pass out, have difficulty breathing, chest pains, or trouble with your speech before or after you faint.