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Syncope is a temporary loss of consciousness that happens due to a decrease in blood flow to your brain. It’s more commonly known as fainting.

Fainting accounts for between 3 and 5 percent of emergency room visits in the United States. An estimated 42 percent of the population will experience a fainting episode during their lifetime.

There are many different kinds of fainting episodes, all with different causes. Read on as we explore the different types of syncope, symptoms to look out for, and what you should do if you faint.

You may experience several symptoms shortly before you faint. Common symptoms can include:

There are several types of syncope, each with a different cause.

Sometimes, though, the cause of fainting can’t be determined. It’s estimated that 10 to 40 percent of fainting cases have an unknown cause.

Let’s take a closer look at some of the most common types of syncope, or fainting episodes.

Reflex syncope, also known as neurally mediated syncope, is the most common type of fainting. It happens when certain reflexes are not properly regulated.

This can cause your heart to slow down and a drop in blood pressure. In turn, this can decrease the flow of blood to your brain.

There are three kinds of reflex syncope:

  • Vasovagal: This happens when your body overreacts to a trigger. There are many types of triggers, which can include things like intense pain, distress, or standing too long. Vasovagal syncope accounts for 50 percent of all cases of fainting.
  • Situational: This type of fainting happens when you perform certain actions, such as laughing, coughing, or swallowing.
  • Carotid sinus: This type of fainting happens when pressure is placed on your carotid artery, located in your neck. Fainting can occur due to certain neck motions, wearing shirts with a tight collar, or shaving.

In people with reflex syncope, fainting is often preceded by symptoms such as:

  • lightheadedness
  • nausea
  • feelings of warmth
  • tunnel vision
  • visual blackout or “grayout”

Cardiac syncope is fainting caused by a problem with your heart. When your heart isn’t working quite as it should, your brain receives less blood. It’s estimated that cardiac syncope causes about 15 percent of fainting episodes.

Several factors can cause cardiac syncope, including:

Common characteristics of cardiac syncope include:

  • experiencing chest pain or heart palpitations before fainting
  • having fainting symptoms while exercising or exerting yourself
  • fainting while you’re lying down

Risk factors for cardiac syncope include:

  • being older than 60
  • being male
  • having heart disease
  • having a family history of heart conditions or fainting

Orthostatic syncope happens due to a drop in blood pressure when you stand up. The drop in blood pressure occurs due to the effects of gravity.

Normally, your brain works to stabilize this. But in orthostatic syncope this doesn’t happen. As a result, it can lead to fainting.

There are many possible causes for this type of fainting. They can include:

Symptoms are usually consistent with the warning signs that are commonly experienced before a fainting episode. However, orthostatic syncope may also happen suddenly, without warning.

This type of syncope happens due to a problem with the blood vessels in and around the brain that can prevent the brain from getting enough blood.

There are a variety of factors that can cause this type of fainting, but they aren’t common causes of syncope. They can include:

Some symptoms that may occur with cerebrovascular causes of fainting include:

  • feeling dizzy or lightheaded
  • headache
  • uncoordinated movements
  • trouble hearing
  • confusion

Risk factors for this type of fainting may include:

  • If you’re feeling faint, lie down. Position yourself so your head is low and your legs are raised. This can help increase the blood flow to your brain. Lying down also lowers your risk of injury if you were to faint.
  • If you can’t lie down, sit down. Depending on the situation, you may not be able to lie down. In this case, sit down and put your head between your knees to increase the blood flow to your brain.
  • Stay lying down or seated until the feelings of faintness pass. Don’t get up too quickly, as this may make you feel faint again.

What to do after fainting

Not all cases of fainting are serious. However, it’s still a good idea to get medical attention and to make sure to have someone else drive you.

In some cases, fainting may be a sign of a serious health condition. You should seek emergency medical attention if you:

If you’re with someone when they faint, check for injuries and whether they’re still breathing. If they’re uninjured, help position them either onto their back with their legs raised or into a comfortable sitting position.

If the person is injured, doesn’t regain consciousness, or isn’t breathing, call 911. Stay with them until help arrives.

To diagnose the cause of your fainting, your doctor will first take your medical history. They’ll ask you about your symptoms, what you were doing when you fainted, and if you’re taking medications or have underlying conditions.

They’ll also perform a physical examination. This can include listening to your heart or taking your blood pressure.

A variety of tests can be used to diagnose the cause of fainting. These tests may include:

  • Electrocardiogram (ECG): An ECG measures the rhythm and electrical activity of your heart using small electrodes. In some cases, you may need to wear a portable ECG device to monitor your heart’s activity over a period of time.
  • Laboratory tests: Blood tests can help identify conditions like diabetes, anemia, or cardiac markers.
  • Tilt-table test: During a tilt-table test, you’ll be secured to a special table. Your heart rate and blood pressure are measured as you’re rotated from lying down to upright.
  • Carotid sinus massage: Your doctor will gently massage your carotid artery, which is located in your neck. They’ll check to see if symptoms of faintness occur when they do this.
  • Stress test: A stress test assesses how your heart responds to exercise. The electrical activity of your heart will be monitored via ECG while you exercise.
  • Echocardiogram: An echocardiogram uses sound waves to create a detailed image of your heart.
  • Electrophysiology: With electrophysiology, small electrodes are threaded through a vein and into your heart to measure your heart’s electrical impulses.
  • Imaging tests: These tests can include a CT scan or MRI, which capture images inside your body. These tests are most often used to look at the blood vessels in your brain when a neurologic cause of fainting is suspected.

There are a number of steps you can take that may help prevent fainting:

  • Don’t skip meals. You may want to eat smaller, more frequent meals throughout the day.
  • Drink plenty of fluids. This may help prevent fainting due to dehydration.
  • Understand if there are external factors or triggers that may cause you to faint. This could include the sight of blood, getting an injection, or intense pain. If possible, try to avoid situations that may trigger a fainting episode.
  • Take your time when standing up. Standing up too quickly can cause a drop in blood pressure and prevent enough blood from flowing to your brain.
  • Avoid shirts with tight collars. This can help prevent carotid sinus syncope.

Fainting happens when your brain doesn’t get enough blood. The medical term for fainting is syncope.

There are several different types of syncope and they all have different causes. These can include problems with your heart, irregular stimulation of specific reflexes, or a drop in blood pressure from standing too quickly.

While not all syncope episodes are serious, you should still contact your doctor if you faint. Be sure to seek emergency medical attention if you faint repeatedly, have underlying health conditions, experience chest pains, or are pregnant.