When to worry about fainting with anaemia

Anaemia means the blood has reduced oxygen-carrying capacity. This can leave you tired, breathless, light-headed, or aware of a fast heartbeat. Fainting occurs when the brain briefly receives too little blood flow, and anaemia may contribute, particularly when it is significant or developing alongside blood loss. Fainting has other possible causes, including heart rhythm problems, dehydration, and low blood pressure, so an episode needs proper assessment rather than being attributed to anaemia automatically.

Lay the person flat and raise the legs if there is no injury that makes this unsafe. Loosen tight clothing, check breathing, and do not give food or drink until they are fully alert. If recovery is incomplete, place them on their side and call emergency services. Once recovered, avoid driving, climbing, or operating machinery until a clinician has reviewed the cause.

Call emergency services for chest pain, severe breathlessness, a racing or irregular heartbeat, seizure-like movements, persistent confusion, new weakness, a serious head injury, fainting during exercise, or heavy bleeding. Seek prompt medical review after any unexplained faint, repeated episodes, black or bloody stools, unusually heavy menstrual bleeding, or worsening exhaustion. A clinician may need to check blood counts, bleeding sources, medicines, blood pressure, and heart rhythm.

Ask what type of anaemia you have, whether bleeding or another condition could be contributing, and which tests are needed. Describe what you were doing before fainting, warning sensations, the time you were unresponsive, injuries, recovery, diet, menstrual or digestive bleeding, and all medicines or supplements.