Before you faint due to vasovagal syncope, you may experience some of the following:
- Skin paleness
- Tunnel vision — your field of vision is constricted so that you see only what's in front of you
- Feeling of warmth
- A cold, clammy sweat
- Blurred vision
During a vasovagal syncope episode, bystanders may notice:
- Jerky, abnormal movements
- A slow, weak pulse
- Dilated pupils
Recovery after a vasovagal episode begins soon after fainting, generally in less than a minute. However, if you stand up too soon after fainting — within 15 to 30 minutes or so — you're at risk of fainting again.
When to see a doctor
Because fainting can be a sign of a more serious condition, such as a heart or brain disorder, you may want to consult your doctor after a fainting spell, especially if you never had one before.
Vasovagal syncope occurs when the part of your nervous system that regulates heart rate and blood pressure malfunctions in response to a trigger, such as the sight of blood. Your heart rate slows, and the blood vessels in your legs widen. This allows blood to pool in your legs, which lowers your blood pressure. This drop in blood pressure and slowed heart rate quickly diminish blood flow to your brain, and you faint.
Common triggers for vasovagal syncope include:
- Standing for long periods of time
- Heat exposure
- The sight of blood
- Having blood drawn
- Fear of bodily injury
- Straining, such as to have a bowel movement
Even with treatment, not all vasovagal syncope episodes can be avoided. If you feel like you might faint, lie down and lift your legs. This allows gravity to keep blood flowing to your brain. If you can't lie down, sit down and put your head between your knees until you feel better.