The most common causes of the phenomenon of sudden fainting while standing are syncope, epilepsy, and sudden collapse seizures. There are also many causes of syncope, commonly there are: 1. Reflex syncope: such as vasovagal syncope, sudden fainting after severe pain. Common causes are upright postural hypotensive syncope, for example, some people squat for a long time, stand up and faint, and even some people suddenly faint when coughing, which are reflex syncope; 2, cardiogenic syncope: as the name implies cardiogenic syncope is the fainting caused by cardiac factors. For example, severe arrhythmias, some people have a particularly slow heartbeat or have heavy conduction block, cardiogenic syncope can occur; 3, cerebral syncope: cerebral syncope is commonly caused by the narrowing of the large cerebral arteries, this phenomenon can occur; 4, other causes of syncope. For example, some people may faint when they have severe anemia, and some people may faint when they breathe faster after getting angry, called hyperventilation syndrome, which can also lead to syncope. Once there are epileptic manifestations accompanied by twitching of limbs, clenching of teeth, foaming at the mouth, or even tongue bite, incontinence and sudden collapse seizures in some people. Once the latter two conditions occur, it is important to see a doctor in the hospital. It is also recommended to go to the hospital in case of syncopal episodes. In addition to the common reflex syncope, further examination must be done to rule out any cardiac or cerebral factors causing the syncope.