What should you know about post coital syncope?

Sexual activity can involve exertion, changes in breathing, heat and a rapid shift from stimulation to rest. In some people this triggers a reflex that lowers blood pressure and heart rate. Fainting can also be associated with [Dehydration](/conditions/dehydration/), [Anaemia](/conditions/anaemia/) or low blood sugar such as [Hypoglycaemia](/conditions/hypoglycaemia/). An irregular rhythm, including [Atrial Fibrillation](/conditions/atrial-fibrillation/), is another reason a clinician may check your heart. The event may be brief, but the circumstances and any injury are clinically relevant.

Lie flat and raise your legs if possible, loosen tight clothing and allow yourself to recover before standing. Do not drive, swim alone or climb until you have been assessed if fainting may recur. Note what you were doing, warning sensations, palpitations, chest discomfort, food and fluid intake, medicines and how long recovery took. Arrange a medical review, particularly after a first episode, a repeat episode or an injury.

Call emergency services for fainting with chest pain, severe breathlessness, sustained palpitations, a severe headache, seizure-like movements, serious injury, confusion, or difficulty speaking or moving. Seek urgent assessment if the blackout happened during exertion, occurred without warning, or there is a known heart condition or a family history of sudden cardiac death.

Ask what tests may clarify the cause, whether medicines or hydration played a part, when sexual activity is safe to resume, and which symptoms should trigger emergency care.