The summer heat, recently the temperature in the Shanghai area has risen to more than 35 degrees Celsius. People suffering from hypertension often feel faint in the head. Because the outdoor temperature is higher, more patients rarely go out to the clinic to prevent heat stroke, so they do not know about their blood pressure and other indicators. In fact, this is very dangerous, blood pressure with the change of temperature will have great ups and downs, so we emphasize that patients with hypertension must learn to self-measurement of blood pressure: blood pressure should be measured regularly, a little discomfort should be measured at any time, according to the results Lei adjust the use of blood pressure medication. As the outdoor temperature rises, the blood vessels of hypertensive patients will dilate and the peripheral resistance will be reduced, so it is more common that the blood pressure will drop even lower when taking the original antihypertensive drugs. Depending on the person, dizziness and lightheadedness will occur when a certain low level is reached, especially when the position changes, and these symptoms are a sign of low perfusion. At what level should blood pressure be reduced or discontinued? It depends on the age, the severity of the complications and the resulting symptoms of hypoperfusion. Generally speaking, blood pressure in hypertensive patients should not be lower than, 110/70 mmHg; in young and middle-aged hypertensive patients without complications, the minimum should not be lower than 100/60 mmHg; in elderly hypertensive patients, especially those aged >80 years, systolic blood pressure should be lowered to 150 mmHg to stop. The danger of low perfusion is not only to cause dizziness and lightheadedness, but also can cause greater damage due to insufficient blood supply to the brain or coronary arteries. Hot weather sweating more, should be timely hydration. Tea or plain water is enough, no need to drink too much other beverages or salt water. Drinks contain too much calories, too much calories cause obesity. Salt water drink too much, salt-sensitive hypertension can make blood pressure rise. Not fully hydrated, blood concentration, blood viscosity increases, can cause brain infarction. Sleep should not be blowing with an electric fan, hot days, skin mucous membrane vasodilatation, excessive blowing fan, skin vascular will be protective contraction can cause a sudden increase in blood pressure. Similarly, the air-conditioned room, the room temperature should not be lowered too low. According to our experience, in mid-summer, many patients who are taking antihypertensive drugs should be adjusted according to the actual measured blood pressure, or reduce a drug, or reduce the amount, and should often monitor the status of blood pressure. The usual outdoor activities, exercise, etc. should be adhered to, but should be avoided in the hot sun, choose in the evening is a better way.