Does low blood pressure cause fainting?

Before fainting, you might notice warmth, nausea, sweating, blurred vision, ringing in the ears, or lightheadedness. Triggers include standing for a long time, rising quickly, dehydration, heat, pain, emotional stress, illness, and some medicines. Fainting can also result from an abnormal heart rhythm, seizure, low blood sugar, or another medical problem, so a new or unexplained episode should be assessed. A clinician may ask about warning symptoms, what you were doing, recovery time, injuries, family history, and medicines.

Lie flat and raise your legs if possible. Loosen tight clothing, keep still, and ask someone to stay with you. After recovery, sit up slowly and do not drive, swim alone, use heights, or operate machinery until a clinician has advised you. Keep a record of the setting, warning signs, food and fluid intake, and any medication taken. Do not change prescribed treatment on your own. Regular fluids and slow position changes may help some people, but the right plan depends on the cause and your health.

Call emergency services if the person does not quickly regain consciousness, has difficulty breathing, chest pain, a severe injury, prolonged confusion, new weakness, trouble speaking, seizure-like movements, or a very fast or irregular heartbeat. Urgent assessment is also needed when fainting occurs during exercise, while lying down, after significant bleeding, or without warning. Anyone with a first episode, repeated episodes, or known heart disease should arrange medical review.

Ask whether you need an examination, blood tests, an electrocardiogram, or blood-pressure checks while changing position. Explain any warning symptoms, injuries, triggers, family history of sudden cardiac death, and medicines or supplements you use.