Sweating in the armpit stains the clothes yellow considering physiological factors as well as color sweating, axillary hair ringworm and other pathological causes. 1. Physiological factors: the human body in the high temperature environment for sports or labor, can lead to a lot of sweat under the armpits, if not replaced and wiped in a timely manner, can lead to sweat in the fatty acids and other organic substances in the air and the chemical reaction, thus causing the clothes stained yellow. Secondly, a large number of carrots and oranges and other carotene-rich foods in a short period of time, the sweat will also lead to the yellowing of clothes. 2. Pathological factors: (1) chromhidrosis: a rare skin disease characterized by colored sweat, common sweat color is yellow, green, brown and blue, so when the patient has chromhidrosis can also lead to underarm sweating to clothes yellow. (2) Tinea capitis: it is a kind of superficial cuticle bacterial infection of armpit hair caused by Corynebacterium, which can lead to the appearance of white, yellow and red granular adherents on the armpit hair, and it is also easy to lead to the yellow staining of clothes when sweating. As there are many reasons for yellowing of clothes due to underarm sweating, it is recommended to visit the hospital in time to find out the cause and follow the doctor’s instructions for treatment.