There are three common reasons for constant sweating on the forehead in summer: the first reason, the initial stage of wind-heat cold symptoms. In this case, there will be cold sweat on the forehead, and the body temperature will first drop and then rise, accompanied by dizziness, headache, cough, phlegm, and runny nose. The second reason, the precursor of heat stroke, such as hot sweat on the forehead all the time, accompanied by reduced blood pressure, fine and rapid pulse, dehydration appearance, dehydration symptoms, flushing, etc., should be considered whether there is a case of heat stroke in the high heat environment in summer. The third reason, hypoglycemic reaction, people are prone to hypoglycemia after losing a lot of body fluids in summer, and their foreheads will keep sweating in the early stage of hypoglycemia. Regardless of which reason the forehead has been sweating in summer, you should be alert, it is best to go to the hospital to avoid affecting or delaying the condition.