Sweating on the forehead may be caused by physiological factors such as strenuous exercise and high-temperature environments, as well as pathologic factors such as upper respiratory tract infections, tuberculosis and hyperhidrosis. 1. Physiological factors: prolonged exposure to high temperatures, strenuous exercise, consumption of too spicy food and other physiological factors, will stimulate the body to sweat to achieve the purpose of maintaining a constant body temperature, so there will be a sweaty forehead. 2. Pathologic factors: (1) Upper respiratory tract infection: in upper respiratory tract infection, viral or bacterial infection will stimulate the body’s immune system to play a role, which may cause fever, making the body temperature too high and dissipate heat through sweating, so there will be the symptom of excessive sweating on the forehead. (2) Tuberculosis: Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, and the clinical process is mostly chronic, often manifested as low fever in the afternoon, night sweats, fatigue, emaciation and other systemic symptoms, which may appear as excessive sweating in the forehead. (3) Hyperhidrosis: Hyperhidrosis is a disease in which the local or generalized skin sweats excessively in normal temperature, which may be caused by autonomic nerve disorder or by certain internal diseases. Patients mainly show increased sweating on the palms of the hands, soles of the feet, armpits, forehead and other areas. Excessive forehead sweating caused by physiologic factors is mostly transient and can disappear on its own after removing the trigger. After eliminating physiological factors, patients with excessive forehead sweating should consult a doctor in a timely manner to clarify the cause of the disease and then carry out treatment for the cause of the disease.