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Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• Introduction to fainting (syncope)
• What causes fainting (syncope)?
• Heart rhythm changes
• Heart structural conditions
• Heart valve conditions
• Sudden cardiac death
• Postural hypotension
• Vasovagal syncope
• Anemia
• Dehydration
• Orthostatic hypotension
• Vertebrobasilar system
• Electrolyte imbalance
• Other medications and drugs
• Pregnancy
• What are the signs and symptoms of fainting (syncope)?
• How is fainting (syncope) diagnosed?
• What is the treatment for fainting (syncope)?
• Can fainting (syncope) be prevented?
• Fainting (Syncope) At A Glance
• Patient Comments: Fainting - Describe Your Experience
• Patient Comments: Fainting (Syncope) - Treatments
• Patient Comments: Fainting (Syncope) - Causes
• Patient Comments: Fainting (Syncope) - Symptoms
• Fainting Index

Electrolyte and hormone abnormalities may also be responsible for syncope; however, these causes are due to their effects on the heart and blood vessels.

Other medications or drugs may also be potential causes of fainting or syncope including those for high blood pressure that can dilate blood vessels, antidepressants that can affect heart electrical activity, and those that affect mental status like pain medications, alcohol, and cocaine.

Syncope is also related to pregnancy. Likely explanations include compression of the inferior vena cava (the large vein that returns blood to the heart) by the enlarging uterus and by orthostatic hypotension.

With fainting (syncope), the patient is unaware that they have passed out and fallen to the ground. It is only afterward that they understand what has happened.

There may be symptoms or signs before the syncopal episode, which may include:

• The person may feel lightheaded, nauseated, sweaty, or weak. There may be a feeling of dizziness or vertigo (with the room spinning), vision may fade or blur, and there may be muffled hearing and tingling sensations in the body.
  
  
• With pre-syncope or a near-faint, the same symptoms will occur, but the person doesn't quite lose consciousness.

During the episode, when the person is unconscious, there may a few twitches of the body which may be confused with seizure activity.

The person may have some confusion after wakening but it should resolve within a few seconds.

After a syncopal episode, there should be a quick return to normal mental function, though there may be other signs and symptoms depending upon the underlying cause of the faint. For example, if the individual is in the midst of a heart attack, he or she may complain of chest pain or pressure.