What should you know about MS and fainting?

Fainting may follow standing for a long time, heat, pain, fear, dehydration, or a sudden drop in blood pressure. Other possibilities include low blood sugar, anaemia, or an abnormal heart rhythm such as atrial fibrillation. MS can affect balance and mobility, but a blackout needs its own assessment; a fall, seizure, or medication effect may also be relevant.

A clinician will want to know what happened before the event, how long you were unresponsive, whether there was shaking or injury, and how quickly you recovered. Witness details can be very useful.

Lie down with your legs raised if you feel faint, loosen tight clothing, and avoid driving or climbing until you have been assessed. Once fully alert, small sips of fluid may help if dehydration is possible and you can drink safely. Record triggers, posture, food intake, medicines, palpitations, and injuries.

Do not give food or drink to someone who is unconscious. Place them safely on their side if breathing normally, check their breathing, and seek emergency help if they do not wake promptly.

Seek emergency help for fainting during exercise, chest pain, severe breathlessness, a racing or irregular heartbeat, serious injury, prolonged confusion, repeated episodes, or failure to regain consciousness. Prompt medical review is also needed if fainting is new, unexplained, or occurs with diabetes or heart disease.

Ask whether your blood pressure, blood count, glucose, medicines, and heart rhythm need checking. Explain any warning symptoms, injuries, family history of sudden cardiac problems, or witness reports of shaking or unusual movements.