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08/23/2024 | Press release | Distributed by Public on 08/23/2024 10:08

Vasovagal Syncope: Causes, Symptoms, and Treatment

Key takeaways:

  • Vasovagal syncope is a common condition where you may faint under certain circumstances. This can happen when the vagus nerve is overstimulated.

  • Vasovagal symptoms include dizziness, lightheadedness, nausea, and sweating. Severe cases may cause syncope, or loss of consciousness.

  • Pain, nausea, fear, and straining for a bowel movement are common causes of vasovagal syncope.

  • Vasovagal syncope can usually be managed with good hydration, squeezing the legs together, and lying down when symptoms start.

olyniteowl/iStock via Getty Images Plus

Have you ever felt a little queasy at the sight of blood? Or gotten dizzy and clammy when you hit your funny bone? Perhaps you've even passed out after vomiting.

If this sounds familiar, chances are good that you experienced a vasovagal reaction. This condition, named for the vagus nerve, happens to about half of all people at some point in their lives. When the reaction is severe, it can cause syncope - a medical term for passing out or fainting.

Most of the time, vasovagal syncope is just a nuisance, but for some people it can lead to serious falls and injuries. Knowing the triggers for vasovagal syncope is the first step to getting the condition under control.

EXPERT PICKS: WHAT TO READ NEXT
  • Dizziness and low potassium: If you feel faint, having your potassium levels checked may lend clues to the cause.

  • Do you always faint when you give blood? Find out what to do about vasovagal syncope when donating blood.

  • Causes of dizziness: Learn about the most common causes of dizziness and when you should seek help.

What causes vasovagal syncope?

To understand vasovagal syncope, a little knowledge of the vagus nerve is helpful. It travels from behind the brain, through the neck, to organs in the chest and abdomen. The vagus nerve is part of the fight-flight-freeze response, and generally it has a calming effect. It belongs to the parasympathetic nervous system, and it helps to:

  • Slow your heart rate

  • Lower your blood pressure

  • Control your rate of breathing

  • Allow normal movement of the digestive tract

Problems happen when the vagus nerve overreacts or is overstimulated. This causes the heart rate and blood pressure to drop so low that blood flow to the brain is reduced.

Things that can bring on vasovagal syncope include:

  • Severe emotional stress

  • Pain

  • Disturbing images

  • The sight of blood

  • Nausea and vomiting

  • Long periods of standing, especially in the heat

  • Straining for a bowel movement

  • Urination, especially in the middle of the night (also known as "micturition syncope")

  • Heavy coughing

Dehydration will often make the symptoms worse. For example, someone with diarrhea from a stomach flu or food poisoning may be more susceptible to a vasovagal reaction.

Why do people get vasovagal syncope?

Although vasovagal syncope is very common, experts aren't clear on why some people get it and others don't. In some cases, especially for men, the problem may be genetic.

So far, there's no cure for vasovagal syncope. So, if you come from a family of fainters, it's important to avoid things that might trigger an episode.

What are vasovagal syncope symptoms?

Vasovagal syncope refers to the loss of consciousness (fainting) that happens with vasovagal symptoms. These symptoms can include:

It's important to recognize the symptoms of vasovagal syncope before they become severe. If your episodes are difficult to manage, you'll likely be referred to a cardiologist, a healthcare professional who specializes in heart conditions.

Does a vasovagal reaction always result in fainting?

Most of the time, vasovagal symptoms won't cause you to faint. But you may feel weak, nauseated, and clammy. Usually, you'll have time to get yourself into a safer position before the symptoms become severe.

Lying down and propping your feet up above the level of the heart will often make you feel better within a few minutes. This simple action helps blood flow back to the brain, which counteracts the effects of low blood pressure. It'll also keep you from falling and hurting yourself.

If your case is more severe, you may pass out suddenly and without warning. This can be dangerous. You could break a bone or suffer a concussion from a hard fall if you aren't able to sit or lie down before losing consciousness.

How is vasovagal syncope diagnosed?

If you experience a fainting episode, it's important to get a medical checkup. That's especially true if the episode happens without warning or while driving, or causes a fall or injury. Vasovagal syncope itself isn't always serious. But it's important to rule out more serious health issues that could cause fainting. These include problems with heart muscle strength or rhythm, or even neurological conditions like seizures.

What to expect

To make a diagnosis, a healthcare professional will ask about any supplements, over-the-counter medications, or prescription medications that you're taking. That way, they can be sure that none of these medications are causing trouble for you.

Your initial testing may include:

Depending on what this first round of tests finds, your healthcare team may order additional tests. You might need an echocardiogram, which can show the heart's strength, check the valves, and look for heart damage.

You may also be asked to wear a heart rhythm monitor. This device records your heart rhythm to check for unusual skips or pauses that might cause you to pass out.

Even more specialized testing might follow, depending on your results and the severity of your symptoms.

What is the treatment for vasovagal syncope?

In most cases, there's no specific vasovagal syncope treatment. You'll be advised to stay well hydrated and avoid the things that can trigger an episode.

Some of the ways to treat episodes of vasovagal syncope include:

Frequently asked questions

Can you die from vasovagal syncope?
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Vasovagal syncope is usually harmless. But a person could be injured during a fall. In rare cases, an underlying heart condition can cause vasovagal syncope. And this heart condition could be fatal.

How long can a vasovagal episode last?
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Vasovagal episodes can last anywhere from a few seconds to a couple of minutes. As soon as a person falls to the floor, their blood pressure increases to normal levels quickly. However, it may take a few minutes to fully restore normal blood flow. So it's important to take it easy after an episode.

Does vasovagal syncope ever go away?
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Yes. Most people will only have one episode of vasovagal syncope. But about 35% of people will continue having episodes throughout their life.

The bottom line

Vasovagal syncope is a common problem that many people experience at some point. In most cases, you can keep yourself safe by staying hydrated, avoiding triggers, and sitting or lying down if symptoms occur. For some people, a regular yoga practice can help manage the condition. If you experience vasovagal symptoms frequently or without warning - or if they cause injury due to falling - be sure to seek help from your primary care provider.

References

Alboni, P., et al. (2007). Is vasovagal syncope a disease?European Pacing, Arrhythmias, and Cardiac Electrophysiology.

Aydin, M. A., et al. (2010). Management and therapy of vasovagal syncope: A review. World Journal of Cardiology.

View All References (8)
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Benditt, D. (2024). Patient education: Syncope (fainting) (beyond the basics). UpToDate.

Jeanmonod, R., et al. (2023). Vasovagal episode. StatPearls.

Krediet, C. P. T., et al. (2002). Management of vasovagal syncope: Controlling or aborting faints by leg crossing and muscle tensing. Circulation.

MedlinePlus. (2022). Cardiac event monitors.

Mitrani, R. D., et al. (2013). The appropriateness of an ischemia evaluation for syncope. Circulation: Cardiovascular Imaging.

Raj, S. R., et al. (2022). Vasovagal syncope needs the "expert touch". Journal of the American College of Cardiology.

Sheldon, R., et al. (2019). Genetic association study in multigenerational kindreds with vasovagal syncope: Evidence for involvement of sex-specific serotonin signaling. Circulation: Arrhythmia and Electrophysiology.

Shenthar, J., et al. (2021). A randomized study of yoga therapy for the prevention of recurrent reflex vasovagal syncope. European Pacing, Arrhythmias, and Cardiac Electrophysiology.

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

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