Types of vasovagal syncope

A trigger can make the nervous system slow the heartbeat, widen blood vessels, or do both. Blood pressure then falls briefly, reducing blood flow to the brain. People may feel warm, nauseated, sweaty, light-headed, or notice narrowing vision before losing consciousness.

Some episodes are mainly triggered by emotion or a medical procedure; others follow standing still, heat, dehydration, pain, or seeing blood. A clinician should not assume every faint is vasovagal: anaemia, an irregular rhythm such as atrial fibrillation, low blood sugar, and other problems can also cause collapse.

At the first warning, lie flat and raise your legs if possible. If lying down is unsafe, sit and lower your head between your knees. Loosen tight clothing, move away from heat, and ask someone to stay with you. After recovery, rise slowly and drink fluids if you are fully alert and able to swallow.

Record what happened, including the trigger, warning symptoms, position, injury, recovery, and any medicines. Avoid driving, heights, swimming alone, or operating machinery until a clinician has assessed an unexplained episode.

Call emergency services for fainting during exercise, chest pain, palpitations, severe breathlessness, seizure-like movements, serious injury, prolonged confusion, or collapse without warning. Urgent assessment is also needed for repeated episodes, a family history of sudden cardiac death, or fainting while lying down.

Ask whether the episode fits a reflex faint, whether blood pressure, heart rhythm, blood count, or glucose should be checked, and which activities to avoid meanwhile. Share witness observations because the recovery pattern can help distinguish fainting from other causes of blackout.