What should you know about random fainting causes?

Fainting, also called syncope, happens when the brain briefly receives too little blood flow. A reflex faint can follow pain, fear, prolonged standing, heat, or straining and may be preceded by nausea, warmth, sweating, or tunnel vision. Dehydration and heat exhaustion reduce circulating fluid. Low blood sugar can bring shaking, sweating, hunger, or confusion. Anaemia may reduce oxygen delivery and cause tiredness or breathlessness. A fast or irregular heartbeat, including atrial fibrillation, can affect circulation and requires medical review. A fall can cause injury even when the underlying trigger is mild.

If warning symptoms begin, lie flat and raise your legs if possible. Loosen tight clothing, move away from heat, and do not stand until you feel fully recovered. Someone with you should check that you are breathing normally and protect your head; do not put food or drink in the mouth of an unconscious person. After recovery, note the setting, posture, warning symptoms, medicines, food, fluids, injuries, and how quickly you returned to normal. Arrange a clinical assessment after any unexplained faint.

Call emergency services if fainting occurs during exercise, with chest pain, severe breathlessness, a pounding or irregular heartbeat, seizure-like movements, severe injury, ongoing confusion, pregnancy, or new weakness or speech trouble. Urgent assessment is also needed if the person does not wake promptly or faints repeatedly. Do not drive until a clinician has advised that it is safe.

Could this have been a reflex faint, a circulation problem, low blood sugar, anaemia, or a rhythm disturbance? Do I need an electrocardiogram or blood tests? How should I reduce the risk of another episode?