The patient suddenly faints and loses consciousness. There are many diseases that may cause this to happen, and the most common clinical diseases are severe cardiac arrhythmia, epilepsy, and vagal reflex syncope, all of which may lead to sudden fainting and loss of consciousness. The patient’s specific disease will be judged based on a series of examination results and whether it is accompanied by other symptoms, as follows: 1. If the sudden fainting and loss of consciousness is caused by epilepsy, often accompanied by twitching of the limbs, foaming at the mouth and turning up of the eyes, the patient will be initially judged and understood by dynamic electroencephalogram. 2. Judgment can be made by dynamic electrocardiogram. 3. If it is vagal reflex syncope leading to sudden fainting and loss of consciousness, judgment can be made by upright tilt test. For specific diseases, it is recommended to go to the hospital for a clear diagnosis and then give relevant treatment according to the disease.