Syncope causes and symptoms

Fainting can follow standing for a long time, heat, pain, fear, dehydration, or a sudden change in posture. It may also be related to hypoglycaemia, anaemia, medicines, or a heart rhythm problem such as atrial fibrillation. Before a faint, some people notice weakness, ringing in the ears, tunnel vision, paleness, or a feeling of warmth. Others lose consciousness without much warning. A brief, clear recovery is reassuring but does not explain the cause, particularly after a first episode.

At the first warning, lie down and raise your legs if possible, or sit with your head lowered. Move away from traffic, stairs, water, and hot surfaces. If another person is unconscious, check breathing, protect the head, and do not give anything by mouth until they are fully awake. Arrange a clinical review and write down the setting, posture, food and fluid intake, medicines, warning symptoms, duration, and recovery.

Emergency help is needed for fainting with chest pain, breathlessness, palpitations, severe headache, one-sided weakness, speech difficulty, seizure-like movements, or a significant injury. Seek urgent assessment if it happens during exercise, while lying down, without warning, or if alertness does not return quickly. Repeated episodes also deserve prompt medical review.

Ask which checks may identify the cause, including blood pressure measurements, heart rhythm assessment, blood tests, and a medication review. Ask how to prevent another episode and which activities should wait until assessment is complete.