Vasovagal syncope (vay-zoh-vay-gul sing-kuh-pee) occurs when you pass out because your body overreacts to certain triggers, such as the sight of blood or extreme emotional distress. may also be called neurocardiogenic syncope.
The trigger for vasovagal syncope causes the heart rate and blood pressure to drop suddenly. that leads to reduced blood flow to your brain, causing you to briefly lose consciousness.
Vasovagal syncope is usually harmless and does not require treatment. but it’s possible to injure yourself during a vasovagal syncope episode. Your doctor may recommend tests to rule out more serious causes of fainting, such as heart problems.
Before you pass out due to vasovagal syncope, you may experience some of the following:
- pale skin
- tunnel vision: your field of vision is narrowed so you only see what is in front of you
- sensation of warmth
- a cold, sticky sweat
- blurred vision
- jerky and abnormal movements
- slow and weak pulse
- dilated pupils
- standing for a long time
- exposure to heat
- see blood
- blood drawing
- fear of bodily injury
- straining, such as to defecate
During an episode of vasovagal syncope, viewers may notice:
Recovery after a vasovagal episode usually begins in less than a minute. however, if you get up too soon after passing out (within 15 to 30 minutes), you run the risk of passing out again.
when to see a doctor
Fainting may be a sign of a more serious condition, such as a heart or brain disorder. You may want to see your doctor after fainting, especially if you’ve never had one before.
Vasovagal syncope occurs when the part of the nervous system that regulates heart rate and blood pressure malfunctions in response to a trigger, such as seeing blood.
Your heart rate slows and the blood vessels in your legs widen (dilate). this allows blood to pool in the legs, which lowers blood pressure. combined, the drop in blood pressure and the slower heart rate quickly reduce blood flow to the brain and you pass out.
Sometimes there is no classic trigger for vasovagal syncope, but common triggers include:
You may not always be able to prevent a vasovagal syncope episode. if you feel faint, lie down and raise your legs. this allows gravity to maintain blood flow to your brain. if you can’t lie down, sit with your head between your knees until you feel better.