The causes of dizziness and brain swelling in hot weather are as follows: First, some hypertensive patients have increased blood pressure due to hot weather, appearing dizziness and brain swelling, and can be given to patients to adjust antihypertensive drugs orally. Second, dizziness and brain swelling in the heat of the day can be seen clinically in patients with low blood pressure, due to the heat of the weather causes the peripheral blood vessels of the body in a dilated state, aggravating the patient’s low blood pressure, the patient will appear dizzy, brain swelling, and in serious cases, falls, it is recommended that patients drink more water to replenish adequate blood volume. Third, for the hot weather dizziness, brain swelling, also seen in some patients with atherosclerosis, vascular stenosis, due to the hot weather leads to vascular spasm, manifested as dizziness, brain swelling, nausea, vomiting and so on in severe cases.