What should you know about different types of syncope?

Reflex syncope can follow pain, fear, heat, prolonged standing or seeing blood; warning symptoms may include nausea, sweating, warmth or tunnel vision. Orthostatic syncope occurs when blood pressure falls after standing, sometimes because of dehydration or medicines. Cardiac syncope is linked to a heart rhythm or structural problem and may occur suddenly, with little warning.

Other conditions can resemble fainting, including a seizure, low blood sugar or a fall without loss of consciousness. Anaemia, dehydration, hypoglycaemia and atrial fibrillation are among the problems a clinician may consider, depending on the history.

If someone faints, lay them flat and raise their legs if there is no injury or breathing problem. Loosen tight clothing, check breathing, and place them on their side if they are vomiting. Do not give food or drink until they are fully alert. After recovery, rise slowly, drink fluids if appropriate, and avoid driving or hazardous activity until the cause has been assessed.

Record what happened before, during and after the episode, including posture, warning symptoms, medicines, injury and recovery time. A witness account can be useful.

Call emergency services for fainting during exercise, chest pain, breathlessness, palpitations, severe injury, prolonged confusion, repeated episodes, or failure to wake promptly. Urgent assessment is also needed when there is no warning, a known heart condition, or a family history of sudden cardiac death. Even a first uncomplicated episode deserves medical review to identify a reversible trigger.

Ask whether your episode fits reflex, orthostatic or cardiac syncope, whether medicines or fluid loss contributed, which tests are needed, and when driving or exercise is safe.