What should you know about vasovagal hypotension?

A trigger such as heat, pain, fear, prolonged standing, dehydration or a medical procedure can activate the vagus nerve and related reflexes. Blood vessels widen and the heart may slow, allowing blood pressure to fall. Light-headedness, nausea, warmth, sweating, pale skin and blurred or narrowing vision can come first.

The term describes a mechanism, not every cause of low blood pressure. Medicines, bleeding, infection, heart problems and other conditions can also cause dizziness or collapse. A first or unexplained episode deserves clinical assessment.

At the first warning, lie down and raise your legs. If lying down is not possible, sit and lower your head, hold onto something stable and ask for help. Avoid walking, driving or climbing until you feel fully recovered. Afterward, rise slowly and drink fluids if you can do so safely.

Note the trigger, posture, warning symptoms and recovery. A GP consultation can review blood pressure, medicines, hydration and other possible contributors. Do not increase salt, stop medicines or use compression clothing without individual advice.

Get emergency help if collapse is accompanied by chest pain, breathlessness, a fast or irregular heartbeat, severe injury, seizure-like activity, prolonged confusion or difficulty speaking. Emergency help is also needed when someone is not breathing normally or does not wake promptly.

Book a medical review for a first faint, repeated episodes, symptoms without a warning, collapse during exercise, or dizziness that is persistent or worsening. These patterns may need checks beyond simple vasovagal hypotension.

Ask which triggers and warning signs fit your episode, whether any medicine could lower your pressure, how to manage future procedures or prolonged standing, and whether you need blood pressure monitoring or other tests.