Dark knees and elbows may be due to melanization and thickening of the stratum corneum caused by prolonged friction, over-exposure to ultraviolet rays, and congenital heredity. Treatment mainly includes general treatment and medication. 1. General treatment: For patients who suffer from prolonged friction or exposure to ultraviolet rays, the first step is to reduce long-term wear and tear on the knees and elbows, and minimize exposure to strong light, especially in summer, so as to provide good sun protection. Secondly, you can use warm water or warm towels to soak these areas and clean them up after the cuticle is softened; you can also eat more vitamin C-rich foods such as oranges and kiwis, which also help whiten the skin. 2. medication: conventional methods are not ideal for people or patients whose knees, arms and elbows are dark and affect their normal work life, you can also consider medication. For example, you can use retinoic acid ointment and salicylic acid preparation in the darker parts of the body, which can effectively remove the thickened stratum corneum and achieve whitening effect. The above medications need to be used under the guidance of a doctor to avoid self-medication. If the symptoms are not relieved after lifestyle modification, you should consult a doctor in time to clarify the cause of the disease and carry out treatment under the doctor’s guidance.