The arm is very itchy when you scratch a lot of small bumps may be hives, pruritus, eczema and other diseases, need to be based on the cause of oral medication, application of drugs and other ways of treatment. 1. Urticaria: exposure to certain allergenic substances, will lead to the patient’s skin metamorphosis, easy to cause the patient’s arm symptoms of itching, there will be red bumps, can be applied locally glycerine lotion, tacrolimus ointment and other medications, to play a role in relieving the itch. 2. Pruritus: the skin is too dry, easy to cause the occurrence of pruritus, will lead to intense itching of the skin, after scratching the patient’s skin will appear red rash, scabs and other symptoms, can be coated with lidocaine cream, you can also take oral loratadine tablets, levocetirizine hydrochloride tablets and other drugs, can play a role in relieving the itch. 3. Eczema: a kind of skin inflammation reaction with intense itching caused by many internal and external factors, which will cause red bumps after scratching the skin. Oral ebastine tablets, diclofenac tadalafil tablets and other antihistamines, local application of diclofenac cream, mometasone furoate cream and other glucocorticoid and hormonal preparations. The arm is very itchy when scratching a lot of small bumps may have other reasons, it is recommended that the patient to the hospital, to clarify the cause, in accordance with the doctor’s instructions standardized treatment.