Light-headedness and sweaty palms


Vasovagal syncope, a frequent cause of fainting episodes, sounds a lot more sinister than it really is

People prone to fainting episodes may be introduced to the term “vasovagal syncope” when discussing their conditions with a physician. Also called reflex syncope or neurally mediated syncope, vasovagal syncope (VVS) is the most frequent cause of fainting in people. Although it sounds ominous, VVS is quite common and there are some recognizable triggers.

It’s important to note that syncope is the medical term for any type of blackout caused by a sudden lack of blood supply to the brain, which is typical of fainting. According to the organization Syncope Trust and Reflex Anoxic Seizures (STARS), VVS is a transient condition resulting from intermittent dysfunction of the autonomic nervous system, which regulates blood pressure and heart rate.

The Mayo Clinic advises that VVS occurs when the body overreacts to certain triggers. These can include the sight of blood, extreme emotional distress, standing for a long time, intense pain, dehydration, or prolonged exertion. During a VVS episode, the vagus nerve, which directly controls heart rate, can increase activity and cause the heart rate to fall, a condition known as bradycardia. Heart rate and blood pressure essentially go haywire in response to one of these triggers. When this occurs, heart rate slows and the blood vessels in the legs dilate. Blood then pools in the legs and lowers blood pressure throughout the body. These combined factors reduce blood flow to the brain and the person briefly loses consciousness.

According to St. Luke’s Hospital, VVS often affects children and young adults. Unlike other types of fainting, VVS is not indicative of underlying problems with the heart or brain. However, doctors may run tests to rule out other conditions.

In addition to avoiding triggers, people can often prevent VVS episodes by recognizing when they may occur. If dizziness, light-headedness, sweaty palms, and dilated pupils occur, a person can usually avoid fainting by lying down and elevating his or her legs. This will help restore proper blood flow to the brain. Also, a paper published in Circulation Journal titled “Usefulness of physical maneuvers for prevention of vasovagal syncope” says squatting and leg-crossing with muscle tensing can be used as a simple and effective preventive maneuver in patients with VVS.

Some people can manage VVS with lifestyle changes, such as taking in more fluids and eating more salt. Others may need medications prescribed by their doctors.

VVS is usually not dangerous, and a person can recover after a few minutes. Blackouts can be dangerous if they occur while driving or if a person falls and injures himself during a VVS episode. People who have recurrent episodes of fainting should speak with their physicians.


Whole body: fainting, lightheadedness, dizziness, low blood pressure, fatigue, or sweating
Heart: fast heart rate, palpitations, or slow heart rate
Also common: blurred vision, fear, nausea, or pallor


Sometimes there is no classical vasovagal syncope trigger, but common triggers include:
Standing for long periods of time
Heat exposure
Seeing blood
Having blood drawn
Fear of bodily injury
Straining, such as to have a bowel movement


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.