Sweat hair on the calf becomes black and long, may be caused by pigmented nevus, endocrine disorders, adverse reactions to topical medications and so on.
1. Pigmented nevus epidermis: it may be related to heredity, which will increase the pigmentation of local skin lesions, accompanied by the growth of hair, and also show that the sweat hair on the calves becomes dark and long.
2. Endocrine disorders: If the daily diet is not controlled, irregular work and rest, emotional instability, it is very likely to trigger endocrine disorders, resulting in an increase in androgens in the body, which will be manifested in the calf hairs become black and long.
3. Adverse reactions to topical drugs: such as long-term topical hormonal drugs, there will be skin atrophy, capillary expansion and hair growth, will also be manifested as calf hair and black and long.
If the calf sweat hair appeared unknown black long, need to go to the hospital in time, under the guidance of the doctor for targeted treatment.