What should you know about fainting with eyes open and stiff body?

Muscle stiffening and an open gaze can occur during a sudden blackout, but they can also appear during a seizure. The distinction depends on the lead-up, length of the stiff phase, breathing, movements and recovery rather than one visible feature. A heart rhythm disturbance, dehydration, anaemia or low blood sugar may be relevant causes of fainting and should be assessed when the event is unexplained.

Write down whether there was warning dizziness, nausea or warmth, whether the person fell suddenly, and whether they could answer questions soon after waking. A video can help only if it can be made safely without delaying first aid.

Keep the person away from sharp edges, support the head and do not force the body straight or restrain it. Do not place anything between the teeth. When stiffness or shaking ends, check breathing and use the side position if the person is breathing but not fully awake. Stay with them and note changes.

Call emergency services if breathing is absent or abnormal, the person cannot be woken, the body remains stiff, episodes recur, there is a serious fall, severe headache, chest pain, new weakness or persistent confusion. Prompt review is appropriate for a first event, an unexplained collapse or an episode without warning.

Ask whether heart tracing, blood pressure checks, glucose testing or other investigations are appropriate. Mention fluid intake, recent vomiting or illness, medicines, anaemia symptoms and any palpitations before the collapse.