What is vasovagal syncope?

The reflex can be triggered by standing for a long time, heat, emotional distress, pain, seeing blood or straining. Warning symptoms may include nausea, sweating, warmth, light-headedness, blurred vision or muffled hearing. A person may lose consciousness briefly and then recover as blood flow returns. Fainting can also have other causes, including dehydration, anaemia, low blood sugar or an abnormal heart rhythm, so the circumstances matter.

Help the person lie flat and raise their legs if there is no injury or breathing problem. Loosen tight clothing, keep the area cool and check that they are breathing normally. Do not give food or drink until they are fully awake. After recovery, sit up slowly and avoid driving, heights or hot showers until the cause has been assessed. Note the trigger, warning symptoms, duration and any injury for the clinician.

Call emergency services if the person is not breathing normally, does not wake promptly, has chest pain, severe breathlessness, a serious injury, a new weakness or trouble speaking, or faints during exercise. Arrange medical assessment for a first faint, repeated episodes, fainting without warning, or a family history of sudden cardiac death. Urgent review is also sensible when palpitations occur before the event.

Ask whether the episode fits vasovagal syncope, whether blood pressure and heart rhythm checks are needed, and which warning signs should prompt urgent help. Discuss hydration, trigger avoidance and when normal activities can safely resume.