Syncope – Fainting


Syncope is the medical term for fainting. Syncope results from a drop in blood pressure or heart rate. It may occur because of certain triggers, such as dehydration, stress, or exhaustion. Recurrent syncope may be the sign of a heart condition. You should contact your doctor to determine the cause of your fainting and receive treatment.


The heart has several large arteries and veins connected to it that branch out and become smaller as they travel throughout your body. Your arteries deliver and veins return blood throughout your body in a process called circulation. Arteries are blood vessels that carry oxygenated blood away from your heart. Veins are vessels that carry deoxygenated blood from your body and lungs back to your heart.

The aorta is the largest blood vessel in your body. The aorta carries all the blood that is pumped out of your heart and through its many branches, distributes blood to all of the organs and throughout the body. The carotid arteries branch off of the aorta and deliver blood to your head and brain. Two coronary arteries branch off the aorta, which supply the heart with oxygen, blood, and nutrients to keep it healthy.


Syncope occurs when a reduction in blood flow to the brain causes a temporary loss of consciousness. The fainting is brief and followed by a complete recovery of consciousness. Syncope can happen because of many reasons. It can result from a sudden drop in blood pressure, which may occur from being dehydrated, exhaustion, heavy sweating, blood loss, or from standing up quickly. Pain, emotional stress, or fear can cause fainting. Certain medications, hyperventilation, and alcohol or illegal drug use can cause syncope. Further, it may occur with urination, a bowel movement, coughing, or after standing or sitting for too long.

In some cases, syncope may be associated with a disorder called neurally mediated syncope (NMS), also referred to as neurocardiogenic, vasovagal, vasodepressor, or reflex mediated syncope. It is more common in children and young adults, but may occur at any age. A drop in blood pressure or heart rate causes the fainting.

In some cases, syncope may be the sign of a serious disorder. Syncope that occurs with exercise, heart palpitations, or irregular heartbeats may be related to a heart problem. People with a family history of recurrent syncope or sudden death may have a higher risk of cardiac related syncope. Syncope related to heart disease can cause stroke, heart attack, or sudden death.


You may feel weak, dizzy, lightheaded, or nauseated prior to fainting. You may turn pale and sweat. You may have a ringing in your ears and sounds may seem like they are fading out. You may have a visual disturbance, such as everything is “graying out.” These symptoms may last for a few seconds before a brief loss of consciousness. Recovery from fainting is rapid, although you may feel nauseous and sweating initially.


Your doctor will start to determine if you simply fainted, had a seizure, or if you have a heart condition. Your doctor will review your medical history and conduct a physical examination and some tests to determine the cause of your fainting. Your doctor may examine your heart, lungs, and nervous system. Your blood pressure will be measured while you are in different positions.

Cardiac tests may be performed if you have recurrent syncope or if your doctor suspects a heart problem. The tests may include a chest X-ray, electrocardiogram (ECG), and echocardiogram. An ECG records the heart’s electrical activity. An echocardiogram uses sound waves to produce an image of the heart on a monitor. An exercise stress test involves monitoring your ECG and blood pressure while you exercise on a treadmill. The exercise stress test provides information about how your heart works with an increased blood flow. You may wear a Holter monitor for periods of 24 hours or more. A loop recorder can also be used to detect for rhythm abnormalities over a long period of time.

Tilt table testing is used to check for sudden drops in blood pressure or heart rate that can cause syncope. For this procedure, you are secured to a table, which will be positioned at different inclines for various periods of time. Your blood pressure and ECG will be recorded.


People with NMS may be treated with medication and may be advised to eat a high-salt diet and drink plenty of fluids. They should sit or lie down when they feel the warning signs of fainting. Wearing compression stockings may help improve circulation. Orthostatic training exercises can be helpful as well. In some cases, a pacemaker may be necessary to help regulate heart function.


You should follow your doctor’s recommendations if you have NMS. If you feel the warning signs of fainting, you should lie down and elevate your legs. It is important to follow your doctor’s guidelines and attend all of your doctor appointments

Am I at Risk

You should talk to your doctor about what triggers your fainting. In some cases, the trigger may be avoided. People with a family history of recurrent syncope or sudden death have an increased risk for syncope caused by a heart condition.


Prolonged syncope may lead to a seizure. Fainting may also be the sign of a serious condition such as a stroke or heart attack. You should call an ambulance, usually be dialing 911, if you suspect that you or someone else is experiencing a stroke or heart attack.


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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.
The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit