There are multiple causes that can lead to sudden headache, dizziness, nausea, and vomiting in patients. First, hypertensive encephalopathy or cerebral hemorrhage can have the above symptoms, where the patient suddenly develops a severe headache, nausea, and jet vomiting accompanied by dizziness. In this case, first monitor your own blood pressure, or go to the nearest clinic or hospital to measure your blood pressure and see if there is any sharp increase in blood pressure. If the above symptoms occur, rush to the nearest hospital for prompt treatment. Second, if dizziness, nausea and vomiting suddenly appear, it may also be central vertigo. The most common cause is cerebral infarction, and along with the above symptoms, there may also be symptoms of neurological deficits, including limb movement disorders, blurred vision and slurred speech. At this time, we should pay high attention to it and seek medical treatment in time. Thirdly, it may be benign paroxysmal positional vertigo, which may also appear as dizziness, nausea, and desire to vomit, but mostly not accompanied by headache.