Vasovagal Syncope: Why It Happens and What to Do

Medically Reviewed By Kevin Martinez, M.D.
Was this helpful?

The correct name for a vasovagal attack is a vasovagal syncope episode. Vasovagal syncope episodes cause a rapid drop in heart rate and blood pressure due to autonomic dysfunction, resulting in decreased blood flow to the brain and fainting. Vasovagal syncope is the most common cause of fainting. The disorder is also known as neurocardiogenic syncope.

A vasovagal syncope episode may occur in a person of any age, but they are more common in children, young adults, and older adults.

A vasovagal syncope episode itself is not serious. However, injury is possible during a fainting episode.

Is it serious?

A vasovagal syncope episode by itself is not serious. However, fainting may accompany a serious or life threatening condition.

Seek immediate medical care (call 911) if fainting happens alongside serious symptoms, such as:

Also, seek immediate care for injuries sustained during a fainting episode.

Seek prompt medical care if you are receiving treatment for vasovagal syncope episodes but mild symptoms recur or are persistent.

What are the symptoms of vasovagal syncope?

The signs and symptoms of vasovagal syncope episodes have a rapid onset and can occur just once or periodically. They vary among individuals.


A vasovagal syncope episode causes a rapid drop in blood pressure and heart rate, which may result in a number of symptoms. The symptoms can vary in intensity among individuals.

Some people who experience vasovagal syncope episodes have mild symptoms, such as lightheadedness, while others may have frequent fainting episodes.

Lying down and elevating the feet if symptoms begin, undergoing therapy to treat feelings of fear or anxiety, and taking all medications as prescribed can all help prevent these episodes.

Common symptoms of vasovagal syncope

A vasovagal syncope episode is associated with a number of common symptoms related to a lack of blood flow to the brain. Examples include:

Visit our heart health hub here.

Serious symptoms that might indicate a life threatening condition

Vasovagal syncope episodes by themselves are not serious. However, fainting may happen because of a serious or life threatening condition. 

Seek immediate medical care by calling 911 if you or someone you are with has any of these life threatening symptoms:

Learn when to go to the hospital for a rapid heart rate here.

What causes vasovagal syncope?

Vasovagal syncope episodes happen due to a rapid drop in blood pressure and heart rate, resulting in a decrease in blood flow to the brain.

Scientists are not entirely sure what causes vasovagal syncope episodes, but they believe that genetics may play an important role.


The following situations can trigger a vasovagal syncope episode:

  • Standing: Prolonged standing is associated with vasovagal syncope episodes because blood may pool in the legs, reducing blood flow to the brain.
  • Heat exposure: Heat exposure can also lead to a vasovagal syncope episode. As blood flows to the body’s periphery to cool it, this may result in decreased blood flow to the brain.
  • Emotions: Heightened emotions, such as panic or fright — including that felt when seeing blood, having blood drawn, or being fearful for your life — may cause a vasovagal syncope episode.
  • Straining: Straining to have a bowel movement can result in a vasovagal syncope episode from the stimulation of the vagus nerve, which lowers the heart rate in some people.
  • Exercise: Another cause of vasovagal syncope episodes is the rapid pooling of blood in the leg muscles after running or doing other strenuous exercises.

How can you treat vasovagal syncope?

The treatment approach for vasovagal syncope episodes depends on the underlying cause of the condition. Typically, treatment includes identifying your triggers and discussing methods to prevent or avoid them.

Other forms of treatment for vasovagal syncope episodes are not usually necessary. However, if episodes are frequent, your healthcare professional can prescribe several treatment options.

Treatment options for vasovagal syncope

Several treatment options can help with recurrent vasovagal syncope episodes. These depend on the individual’s underlying medical condition(s) and the exact cause of their vasovagal syncope episodes. Examples include:

  • medications, including antidepressants and blood pressure drugs
  • methods to prevent the pooling of blood in the legs, such as:
    • wearing elastic stockings
    • contracting the leg muscles while standing
    • walking in place to use the leg muscles
    • consuming plenty of fluids
  • surgical procedures, such as the insertion of a pacemaker

Reducing your risk of vasovagal syncope episodes

You may be able to lower your risk of vasovagal syncope episodes by:

  • lying down and elevating your feet if a vasovagal syncope episode is beginning
  • participating in stress reduction techniques or therapy to reduce your response to triggers
  • understanding the potential triggers of your vasovagal syncope episodes

What are the potential complications of vasovagal syncope?

Possible complications of vasovagal syncope include:

  • disability from a fall during a fainting episode
  • injury from falling
  • poor quality of life

You can help minimize your risk of serious complications by following the treatment plan that you and your healthcare professional design specifically for you.


Vasovagal syncope episodes involve fainting due to a rapid drop in heart rate and blood pressure. This causes reduced blood flow to the brain.

These episodes are not usually serious, but your doctor may want to determine if there is an underlying cause of the fainting. Complications do include falling from fainting, which may cause injuries.

You can prevent vasovagal syncope episodes by using methods to prevent blood from pooling in the legs, including wearing compression stockings and avoiding standing for long periods of time.

Was this helpful?
Medical Reviewer: Kevin Martinez, M.D.
Last Review Date: 2022 Mar 11
View All Heart Health Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.