Hand scratching the skin after the bumps are still itchy, most commonly seen in urticaria, skin scratches, insect bite dermatitis and so on. 1. Urticaria: The cause of urticaria is complex, if you have an allergy to seafood, and dietary intake of fish, shrimp, crab meat, may cause urticaria-like changes. The skin develops a pronounced itching sensation, and scratching leads to localized bumps. 2. Scratch skin disease: Scratch skin disease, also known as artificial urticaria, is a subtype of urticaria, in which the patient’s skin is mechanically stimulated, resulting in the appearance of red skin, itching, occasionally accompanied by redness and swelling. 3. Insect bite dermatitis: insect bite dermatitis, also known as pimple urticaria and pimple dermatitis, is a common clinical allergic skin disease. Mosquito bites or contact with insect secretions, saliva, resulting in an allergic reaction to the skin, the local may appear in clusters or scattered red air masses like macules. Hand scratching the skin with obvious bumps is mostly seen in skin-related diseases. It is recommended to reduce the adverse stimuli and go to the dermatology department of the hospital.