The black spots left after scratching the skin with small bumps that are itchy refer to inflammatory hyperpigmentation, and the causes include eczema, contact dermatitis, pigmented nevus, papular urticaria, and so on, and different medications can be chosen according to different diseases. 1. Eczema: is caused by a variety of internal and external factors of the superficial dermis and epidermal inflammation, can appear erythematous papules with itching, inflammatory factors to stimulate the melanocyte proliferation, so there is inflammatory hyperpigmentation, can be used externally with glucocorticosteroid cream, such as compound dexamethasone cream coated with treatment. 2. Contact dermatitis: is due to contact with certain exogenous substances, in the skin mucous membrane contact parts of the acute or chronic inflammatory reaction. Repeated exposure of the skin to sensitizers for a long period of time can also lead to inflammatory pigmentation, the need to stay away from sensitizers, oral loratadine and other drugs anti-allergy treatment. 3. papular urticaria: mosquito bites caused by intense itching, scratching can also cause inflammatory hyperpigmentation, external glucocorticoids such as mometasone furoate, oral antihistamine drugs such as loratadine treatment. Skin pimples are very itchy after scratching to stay black spots more reasons, it is recommended to seek medical attention in a timely manner, under the guidance of the doctor for treatment, do not take medication without authorization.