Does anaemia cause fainting?

Fainting happens when the brain briefly receives too little blood flow. Anaemia can reduce the blood's oxygen-carrying capacity, which may make lightheadedness or collapse more likely during exertion, standing, illness, or blood loss. The underlying cause of anaemia matters: possibilities include iron deficiency, vitamin deficiency, ongoing bleeding, or another illness.

A blackout can also result from dehydration, a sudden blood-pressure drop, low blood sugar, seizure, or a heart rhythm problem. A clinician may ask what happened before and after the event, examine you, check blood pressure, and arrange blood tests or heart tests. Do not use the event alone to identify its cause.

If someone faints, lay them flat and raise their legs if there is no injury, then check that they are breathing normally. Do not give food or drink until they are fully alert. Once recovered, avoid driving, heights, and swimming alone until a clinician has advised you. Write down warning symptoms, posture, activity, injuries, and recovery time.

Arrange prompt medical review after any unexplained faint, even if you feel well afterwards. Take details of medicines, recent illness, fluid intake, bleeding, and any known anaemia to the appointment.

Call emergency services if the person does not quickly regain awareness, has difficulty breathing, chest pain, a severe headache, seizure-like movements, new weakness, an irregular heartbeat, serious injury, or heavy bleeding. Urgent assessment is also needed when fainting occurs during exercise, while lying down, or with a family history of sudden cardiac death.

Ask whether anaemia could explain the episode, which tests will look for blood loss or nutritional deficiency, and whether your heart rhythm or blood pressure needs checking. Ask when it is safe to drive and which warning symptoms should lead you to emergency care.