Feeling like you might faint

Near-fainting may cause light-headedness, blurred or narrowing vision, nausea, sweating, warmth, weakness, or ringing in the ears. It can follow standing quickly, prolonged standing, heat, pain, fear, dehydration, or not eating. Anaemia can reduce oxygen delivery and make exertion tiring. Hypoglycaemia may cause shakiness, sweating, hunger, and confusion, especially in someone using diabetes treatment. An abnormal rhythm such as atrial fibrillation is another possible cause, so the context and accompanying symptoms matter.

Stop walking and lie flat with your legs raised, or sit and put your head between your knees if lying down is not possible. Do not drive, climb, or stand suddenly while symptoms continue. Once fully alert, sip water; if you may have missed food and can swallow safely, take a snack. Someone who has actually fainted should be placed safely, monitored, and not given food or drink until fully awake. Recurrent episodes deserve a clinical review.

Call emergency services for chest pain, severe breathlessness, a racing or irregular heartbeat, seizure-like movements, serious injury, new weakness, trouble speaking, confusion, or fainting during exercise. Seek urgent assessment if you faint while pregnant, have known heart disease, remain unwell after recovering, or cannot keep fluids down. A clinician can check blood pressure lying and standing, heart rhythm, blood count, glucose, and other causes when appropriate.

What was I doing and feeling immediately before the episode? Had I eaten and drunk normally? Could blood pressure, anaemia, glucose, or heart rhythm explain it, and should I change any medicine?