You are currently viewing Syncope. What causes fainting? Should it worry you?
Two woman looking after unconscious woman. Getty Images

Syncope. What causes fainting? Should it worry you?

We define syncope as a transitory loss of consciousness followed by unprompted recovery. In brief, syncope implies fainting. In many instances, this happens suddenly: at other times, you may feel dizzy, lightheaded, sweaty, nauseated, or have blurred vision.

Syncope occurs when blood flow to the brain reduces. It is scary and often prompts a hospital visit. Occasionally, there’s no cause for alarm; however, you cannot ascertain this assertion unless you see a clinician because some causes of syncope deserve evaluation. It may mimic a stroke or seizure.

In about half of all cases, syncope results from a sudden dilatation of blood vessels and a reduction in the heart rate (bradycardia). We call it vasovagal syncope (common faint). Prolonged standing, extreme fatigue, stress, excruciating pain: a hot environment, and crowded places are common precursors.

Your blood pressure may suddenly fall upon standing (orthostatic hypertension). Straining may reduce blood flow to the brain and cause fainting, and so can coughing, urination, postprandial, or swallowing.

Rarely, your brain blood vessels may be weak, leading to syncopal episodes (vertebrobasilar insufficiency). Also, you may suffer from arrhythmias or valvular abnormalities. You may have a heart block, aortic stenosis, myocardial infarction, pulmonary embolism, or hypertrophic cardiomyopathy.

It is imperative to differentiate syncope from these conditions (mimics): seizures, hypoxia, anaemia, hypoglycaemia, and panic attacks.

Because of the mimics and close relation of syncope to cardiovascular disorders, it should warrant investigations in the event of unclear history and physical exam findings. The clinician may order a complete blood count, blood glucose, and electrolytes to rule out anaemia, hypoglycaemia, and electrolyte imbalances. At the very least, you should have electrocardiography to ascertain the integrity of your heart function. The clinician may also order an echocardiogram with or without a Holter monitor.


Angina. It’s imperative to understand this type of chest pain.

A syncope that’s indistinguishable from a seizure may warrant electroencephalography. Brain imaging is vital in cases of vertebrobasilar insufficiency.

A tilt table test is crucial in people with recurrent syncopal episodes without a brain or cardiovascular disorder.

Treatment of syncope focuses on the cause. However, regardless of the aetiology, the person nearby should help you sit or lay down quickly and raise your legs. Stay in a horizontal position and do not quickly rise. Seek medical attention if you’ve sustained any injuries.

It is imperative that you avoid stressful events if you are prone to syncopal attacks. The clinician may reduce or stop any drug that may be causing syncope. Keep yourself hydrated to prevent dehydration. Do not undermine any episode of fainting. Talk to your clinician and rule out a few sinister aetiologies, especially those related to the heart and brain.

Syncope is not contagious. Do not hesitate to offer a helping hand to the person who has fainted.

For more information, visit UpToDate or read this article.



MBChB (MUK), Graduate Fellow, Department of Physiology, Makerere University Founder and Content Creator Peer reviewer, Associate Editor

Leave a Reply