What is syncope?

Syncope (pronounced “sin ko pea”) is the medical term for fainting or passing out. It is caused by a temporary drop in the amount of blood that flows to the brain.

Syncope can happen if you have a sudden drop in blood pressure, a drop in heart rate, or changes in the amount of blood in areas of your body. If you pass out, you will likely become conscious and alert right away, but you may be feel confused for a bit.

Autonomic Nervous System (ANS)

The ANS automatically controls many functions of the body, such as breathing, blood pressure, heart rate and bladder control. Most times, these things happen without us noticing.

How common is syncope?

Syncope is a common condition. It affects 3% of men and 3.5% of women at some point in life. Syncope is more common as you get older and affects up to 6% of people over age 75. The condition can occur at any age and happens in people with and without other medical problems.

Types of Syncope

There are several different types of syncope. The type you have depends on what causes the problem.

Vasovagal syncope (also called cardio-neurogenic syncope)

Vasovagal syncope is the most common type of syncope. It is caused by a sudden drop in blood pressure, which causes a drop in blood flow to the brain. When you stand up, gravity causes blood to settle in the lower part of your body, below your diaphragm. When that happens, the heart and autonomic nervous system (ANS) work to keep your blood pressure stable.

Some patients with vasovagal syncope have a condition called orthostatic hypotension. This condition keeps the blood vessels from getting smaller (as they should) when the patient stands. This causes blood to collect in the legs and leads to a quick drop in blood pressure.

Situational syncope

Situational syncope is a type of vasovagal syncope. It happens only during certain situations that affect the nervous system and lead to syncope. Some of these situations are:

  • Dehydration
  • Intense emotional stress
  • Anxiety
  • Fear
  • Pain
  • Hunger
  • Use of alcohol or drugs
  • Hyperventilation (breathing in too much oxygen and getting rid of too much carbon dioxide too quickly)
  • Coughing forcefully, turning the neck, or wearing a tight collar (carotid sinus hypersensitivity)
  • Urinating (miturition syncope)

Postural syncope (also called postural hypotension)

Postural syncope is caused by a sudden drop in blood pressure due to a quick change in position, such as from lying down to standing. Certain medications and dehydration can lead to this condition. Patients with this type of syncope usually have changes in their blood pressure that cause it to drop by at least 20 mmHg (systolic/top number) and at least 10 mmHg (diastolic/bottom number) when they stand.

Cardiac syncope is caused by a heart or blood vessel condition that affects blood flow to the brain. These conditions can include an abnormal heart rhythm (arrhythmia), obstructed blood flow in the heart due to structural heart disease (the way the heart is formed), blockage in the cardiac blood vessels (myocardial ischemia), valve disease, aortic stenosis, blood clot, or heart failure. If you have cardiac syncope, it is important to see a cardiologist for proper treatment.

Neurologic syncope

Neurologic syncope is caused by a neurological condition such as seizure, stroke or transient ischemic attack (TIA). Other less common conditions that lead to neurologic syncope include migraines and normal pressure hydrocephalus

Postural Orthostatic Tachycardia Syndrome (POTS)

Postural-Orthostatic Tachycardia Syndrome is caused by a very fast heart rate (tachycardia) that happens when a person stands after sitting or lying down. The heart rate can speed up by 30 beats per minute or more. The increase usually happens within 10 minutes of standing. The condition is most common in women, but it can also occur in men.

Unknown Causes of Syncope

The cause of syncope is unknown In about one-third of patients. However, an increased risk of syncope is a side effect for some medications.

What are the symptoms of syncope?

The most common symptoms of syncope include:

  • Blacking out
  • Feeling lightheaded
  • Falling for no reason
  • Feeling dizzy
  • Feeling drowsy or groggy
  • Fainting, especially after eating or exercising
  • Feeling unsteady or weak when standing
  • Changes in vision, such as seeing spots or having tunnel vision
  • Headaches

Many times, patients feel an episode of syncope coming on. They have what are called “premonitory symptoms,” such as feeling lightheaded, nauseous, and heart palpitations (irregular heartbeats that feel like “fluttering” in the chest). If you have syncope, you will likely be able to keep from fainting if you sit or lie down and put your legs up if you feel these symptoms.

Syncope can be a sign of a more serious condition. So, it is important to get treatment right away after you have an episode of syncope. Most patients can prevent problems with syncope once they get an accurate diagnosis and proper treatment.

What causes syncope?

Syncope can be caused by many things. Many patients have a medical condition they may or may not know about that affects the nervous system or heart. You may also have a condition that affects blood flow through your body and causes your blood pressure to drop when you change positions (for example, going from lying down to standing).

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