Brown spots on the forehead may be caused by seborrheic keratosis, florid chaffing rash, etc., and should seek medical attention in a timely manner to clarify the cause of the disease. 1. Seborrheic keratosis, mostly seen in people over 40 years old, its main cause is skin aging, ultraviolet radiation, genetic susceptibility, patients may have brown spots on the surface of the body, the color can be gradually deepened, can be treated by laser, cryotherapy method. 2. maculopapular furuncle: brown spots on the forehead may also be caused by malassezia infection of the skin maculopapular furuncle, which is a pore-centered round or oval brown patch or hypopigmented patches, clear borders, can be used externally with ketoconazole cream and other medications for treatment. All of the above medications and treatments should be administered under a doctor’s supervision.