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What is vasovagal syncope?
Vasovagal syncope is the most common cause of fainting. It happens when your blood pressure or heart rate drops suddenly. Fainting can also occur if the amount of blood in areas of your body changes suddenly. All of these situations reduce blood flow to the brain, causing you to faint or pass out.
The dip in blood pressure or heart rate is usually temporary. Most people are unconscious for 15 seconds or less. Vasovagal syncope is rarely life-threatening. The main risk is that you might injure yourself when you faint.
Are there any warning signs of vasovagal syncope?
People sometimes notice warning signs of vasovagal syncope called a prodrome. The signs usually appear 30–60 seconds before you faint. Some early warning signs include:
- Suddenly feeling tired
- Excessive sweating
- Dizziness or lightheadedness
- Ringing or buzzing in the ears
- Visual changes like tunnel vision
What to do if I have a prodrome or warning sign?
The first thing to do is to get to a safe area like your bed or a couch. Ideally, you should lie down with your legs raised but sitting or squatting may also keep you from fainting. Don’t let anyone help hold you up in a standing position when you feel warning signs of vasovagal syncope. Staying standing can lengthen the time you are unconscious if you do faint.
Once you’re in a safe place, do movements that encourage blood flowing to the brain. These are called isometric counterpressure maneuvers. Examples include:
- Crossing your legs while tensing the muscles in your leg, abdomen, and buttock.
- Tightly gripping a rubber ball or similar object.
- Tightly gripping one hand with the other while pulling them against each other.
Avoid potential triggers
There are many triggers of syncope, including:
- Intense emotion
- Forceful coughing
- Straining during a bowel movement
- Heat exposure
- Physical exertion
- Standing after sitting, lying down, or bending
To reduce your risk of fainting, you can try to avoid these triggers:
- Take cough suppressant medication if coughing makes you dizzy or faint.
- Use stool softeners to prevent straining during bowel movements.
- Avoid drinking too much fluid (especially alcohol) before you go to bed to lower the risk of fainting while urinating.
- Avoid standing for prolonged periods of time.
- Drink plenty of water to avoid becoming dehydrated.
- Don’t skip meals, which can cause dips in blood sugar.
- If you faint when getting a vaccination or giving blood, ask the healthcare provider if you can lie down during the process. Don’t look at the needle and try to distract yourself.
- If you faint while swallowing, don’t gulp cold drinks or take big bites when you eat.
- Quit smoking.
Treat conditions that make you prone to fainting
Several types of medical conditions can increase your risk of fainting. If you tend to faint, it may be a sign that you have one of these underlying health problems.
- Anemia is when the body doesn’t make enough red blood cells or loses too many red blood cells. This can reduce the amount of oxygen that gets to your tissues, causing dizziness and fainting.
- Orthostatic hypotension is a form of low blood pressure that causes lightheadedness and fainting when you stand after sitting or lying down.
- Diabetes. When blood sugar levels get low (because of issues with insulin), it can cause dizziness and fainting.
- Postural orthostatic tachycardia syndrome (POTS) is a circulation disorder that causes dizziness when you stand up.
- Pregnancy can make some people prone to fainting from normal changes in circulation and blood volume.
- Certain medications can also increase the risk of fainting, like antidepressants, anti-seizure medications, sedatives, and blood pressure medications. If you faint while on any of these medications, talk to your healthcare provider.
Keeping blood volume high
- Drink more fluids, ideally water or low-carbohydrate electrolyte-containing beverages.
- Wear compression stockings. These tight-fitting garments compress the legs to improve blood circulation in the legs, promoting blood flow to the heart.
- If your sodium (salt) levels are low, your doctor may recommend high sodium-containing food, drinks, or salt or electrolyte tablets.
A research review published in Complementary Therapies in Clinical Practice showed that practicing yoga may help reduce dizziness and fainting in people who have vasovagal syncope regularly.
What should I do if someone else faints?
Move the person to a safe space, ideally where they can lie down with their legs elevated, like on a bed, couch, or the floor. Lying down with legs raised helps blood return to the heart. Helping them move them to a chair is also an option, but try to have them sit with their head between their legs.
Check the person’s pulse and breathing. If those are irregular, it may be a sign of cardiac arrest and you should call 911. Other concerning signs that the person is experiencing a serious medical issue include seizure-like or jerky muscular movements, loss of bladder or bowel control, and being unconscious for more than a minute.
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