Feeling faint but staying conscious

Near-fainting can cause light-headedness, weakness, sweating, nausea, blurred or tunnel vision, muffled hearing and a feeling that the room is moving. It may follow standing quickly, prolonged standing, heat, pain, emotional stress, illness or poor intake. Dehydration, low blood sugar, anaemia and an abnormal heart rhythm can produce similar sensations. Remaining conscious does not prove that the trigger is harmless, especially when symptoms are sudden or occur during exertion.

Stop what you are doing and lie flat with your legs raised. If you cannot lie down, sit and place your head between your knees. Ask someone to stay nearby, loosen restrictive clothing and move to a cooler area. Once symptoms settle, drink fluids and eat a snack if swallowing is safe. Rise in stages, and do not drive, climb or return to exercise until you feel normal.

Get emergency help for chest pain, breathlessness, severe palpitations, one-sided weakness, trouble speaking, seizure, severe headache or collapse. Seek prompt assessment when near-fainting happens during exercise, while lying down, after an injury, or repeatedly without a clear trigger. A clinician can review posture, medicines, blood pressure, glucose and heart rhythm.

Ask whether this is near-fainting or another problem, what patterns to record, and whether testing is appropriate for blood count, glucose or heart rhythm.