Vasovagal syncope triggers

A trigger can prompt an exaggerated automatic response. Blood vessels widen and the heart may slow, so the brain receives less blood for a short time. You might feel hot, pale, sweaty, nauseated, dizzy, or notice greyed vision before losing consciousness. The warning can last only moments, so sit or lie down as soon as it appears.

Triggers differ between people and may combine. A warm crowded room, standing after little fluid, or seeing blood while hungry can be more provocative than any one factor alone. Anaemia, dehydration, hypoglycaemia, and heart rhythm problems can also cause similar symptoms and should not be assumed to be a simple trigger pattern.

Learn your earliest warning sign and act immediately: sit down, or lie flat with your legs supported if comfortable. Drink regularly, avoid skipping meals, cool down in hot settings, and move your legs rather than standing motionless. Tense the muscles of your legs and arms for short periods if you are able and symptoms have just begun.

Tell a companion what to do if you become unresponsive: protect you from nearby hazards, check that you are breathing normally, and seek help if recovery is not prompt. Note the setting, activity, food and fluid intake, warning symptoms, and recovery time.

Get emergency help for fainting during exercise, chest pain, breathing difficulty, severe injury, seizure-like movements, persistent confusion, a new irregular heartbeat, or no quick return to normal awareness. Urgent assessment is needed for fainting without warning or a first episode with no clear context.

Book a clinical review when episodes recur, happen while sitting or lying down, follow a new medicine, or interfere with daily activities. A clinician can distinguish a vasovagal pattern from low blood pressure, anaemia, dehydration, hypoglycaemia, or a rhythm problem.

Ask which triggers fit your history, whether you need blood pressure, blood, or heart-rhythm checks, and how to manage work, travel, exercise, or medical procedures that have brought on warning symptoms.