fainting

Fainting, or syncope, is a brief loss of consciousness with spontaneous recovery, caused by a temporary reduction in blood flow to the brain. It is a symptom rather than a disease, and most episodes are not life-threatening, though some underlying conditions require urgent evaluation.

The most common type is vasovagal syncope, triggered by standing for long periods, heat, pain, fear, or emotional stress. The body temporarily overreacts to these stimuli, causing blood vessels to widen and heart rate to slow, reducing cerebral blood flow and leading to fainting.

Other causes include orthostatic hypotension (a drop in blood pressure when standing, often due to dehydration, medications, or aging), cardiac syncope from arrhythmias or structural heart disease, seizures, metabolic problems such as hypoglycemia, or neurologic disorders. Cardiac causes carry a higher risk of serious outcomes and require prompt assessment.

Common warning signs before fainting include lightheadedness, dizziness, blurred or tunnel vision, nausea, sweating, and palpitations. After recovering, fatigue or confusion may persist briefly.

Evaluation typically includes a medical history, physical examination, and an electrocardiogram. Blood pressure measurements, including orthostatic testing, are common. Additional tests (blood work, echocardiography, rhythm monitoring) are guided by findings. Red flags prompting urgent care include chest pain, prolonged loss of consciousness, focal weakness or numbness, new confusion, injury, or fainting during exertion.

Management focuses on safety during episodes and addressing underlying causes. Acute fainting: lie down and raise the legs to restore blood flow. For recurrent, vasovagal episodes: avoid triggers when possible, stay hydrated, consider increasing salt intake if advised, and perform counterpressure maneuvers (leg crossing, handgrip, tensing). Medications or devices are rarely needed and depend on the specific diagnosis.

Prognosis is generally favorable for benign causes, especially in younger people, but recurrent episodes and cardiac or neurologic conditions require ongoing evaluation and management.