Many friends will find that there is dirt on the armpit hair and/or pubic hair, often accompanied by sweating and odor, the odor intensifies when sweating, obvious in summer after local sweating or bathing, winter or local dryness to reduce, but how to wash with water can not be washed off, that hair on the dirt in the end is what, how should remove it? In fact it a skin disease, we call it armpit hair ringworm, by is a shallow infection of the axillary or pubic hair caused by slender rod-shaped bacilli. Moist and sweaty armpits and pubic areas and poor hygiene are important triggers for tinea capitis. The bacillus cereus grows within and between the cells of the hair epidermis and can invade the hair cortex but not the hair roots or skin, so the affected area has normal skin. Axillary ringworm occurs most often in axillary and pubic hair, with axillary hair being the most common, while other parts of the hair are generally not susceptible to invasion. It occurs most often in warm climates and in people who sweat a lot. The clinical manifestation is the appearance of yellow, black, or red nodular particles on the hair shaft of the axillary or pubic hair, with yellow being the most common. These nodules are almost always dense, slender rod-shaped rods that sheath the hair shaft, causing it to lose its luster and become brittle and easily broken, while the affected skin has no abnormalities and is usually asymptomatic. Due to the different color of the nodules, the sweat can be yellow, black or red, and the color sweat produced can contaminate the underwear. Differential diagnosis: This disease needs to be differentiated from pubic lice. Pubic lice: It is a skin contact infectious parasitic disease caused by the itching of the skin near the bite of pubic lice parasitic on human pubic hair, with grayish-white sand-like particles (lice eggs) and moving pubic lice adhering to the pubic hair, with scratches and blood scabs on the skin, and intense itching at night. Treatment: Pay attention to local dryness and ventilation. First need to shave the affected axillary hair and pubic hair, and simply shave the axillary hair, pubic hair, hair grows again, the hair stem will still appear yellow, black or red nodular particles, so after the removal of hair local need to use topical 5% sulfur cream, mupirocin ointment, fusidic acid cream, erythromycin cream, etc.. If the local sweating, you can give 1% formalin solution. Prevention: Keep the area clean and dry, pay attention to the hygiene of the armpit and pubic area. Underwear, ‘bed sheets, etc. need to be boiled and disinfected before use, avoid sharing towels, bath towels, etc. with others.