When should you see a doctor about fainting?

Fainting, also called syncope, is a brief loss of consciousness caused by reduced blood flow to the brain. It can follow standing quickly, heat, dehydration, pain, or low blood sugar, but it can also be linked to an abnormal heart rhythm or another medical problem. A first episode deserves a clinical history and examination, especially if no clear trigger is present.

Lie flat with your legs raised until you feel fully recovered, then rise slowly. Record what you were doing, your position, warning sensations, medicines, food and fluid intake, and how long recovery took. Avoid driving, heights, swimming alone, or machinery until a clinician has advised you. Do not give food or drink while someone is unconscious.

Call emergency services if fainting occurs during exercise or while lying down, or with chest pain, severe breathlessness, palpitations, a severe headache, weakness on one side, confusion, prolonged unconsciousness, seizure-like movements, or a serious injury. Seek prompt assessment for bleeding, pregnancy, diabetes, known heart disease, or a family history of sudden cardiac death. Possible contributors include Postural Hypotension, Anaemia, Atrial Fibrillation, Dehydration, Epilepsy, Heat Stroke, and Hypoglycaemia.

Ask whether your episode sounds like fainting, which medicines or conditions could contribute, whether you need heart monitoring or blood tests, and when normal activities can safely resume.