Melanin deposits on both sides of the thighs may be caused by physiological factors such as excessive friction, or may be caused by post-inflammatory hyperpigmentation, acanthosis nigricans and other diseases, which can be improved by general treatment, medication and other means. 1. Physiological factors: If the melanin precipitation is caused by excessive friction on both sides of the thighs, patients need to wear loose and comfortable pants. You can also use hydroquinone cream externally as prescribed by the doctor, which has the effect of inhibiting the metabolism of melanin cells. 2. Post-inflammatory hyperpigmentation: For post-inflammatory hyperpigmentation caused by melanin deposits on both sides of the thighs, daily attention needs to be paid to sun protection. Patients can follow the doctor’s instructions oral niacinamide, tranexamic acid and other drugs, can inhibit the proliferation of melanocytes. Can also be used externally external hydroquinone, deoxy arbutin, can inhibit melanin production. 3. Acanthosis nigricans: If acanthosis nigricans causes melanin precipitation on both sides of the thighs, you need to eat a healthy diet, exercise properly and correct obesity. Patients can follow the doctor’s instructions for external use of hydroquinone cream, cod liver oil ointment and other drugs, with the role of reducing hyperpigmentation. There are many reasons that lead to melanin precipitation on both sides of the thighs, and it is recommended that patients go to the hospital, clarify the cause of the disease, and standardize the treatment.