What should you know about fainting causes?

Fainting, also called syncope, happens when the brain briefly receives too little blood flow. Standing for a long time, heat, pain, fear, or a sudden emotional shock can trigger a reflex that lowers blood pressure. Not eating, vomiting, diarrhoea, or heavy sweating can contribute through dehydration or low blood sugar. Anaemia may reduce oxygen delivery, while an irregular rhythm such as Atrial Fibrillation can affect circulation. A clinician may ask what happened before the episode, whether there was injury, and how quickly you recovered.

Lie flat and raise your legs if possible. Loosen tight clothing and move away from heat. Do not stand quickly after you feel better. If you are fully awake and able to swallow, sip fluids and eat something if you have missed a meal. Write down warning symptoms, activity, medicines, food and drinks, and the length of recovery; this helps assessment. Arrange medical advice after a first episode or any unexplained recurrence.

Call emergency services if the person remains unconscious, has trouble breathing, chest pain, a severe headache, new weakness, confusion, a seizure, or a serious injury. Urgent assessment is also needed when fainting occurs during exercise, while sitting or lying down, or with a fast or irregular heartbeat. Do not give food or drink to someone who is not fully alert.

Ask whether your blood pressure, heart rhythm, blood count, glucose level, medicines, or hydration need checking. Mention family history of sudden cardiac problems and describe any palpitations, bleeding, weight change, or repeated dizziness.