The arm itchy scratched with small bumps, if eczema caused, can use boric acid solution, esacridine solution; if hives caused, can use cetirizine, loratadine and so on. 1. eczema: arm itchy scratching after small bumps, if the bumps are small red rash, after the appearance of the general consideration of eczema, can be used externally boric acid solution, ezacrine solution, potassium permanganate solution, resorcinol solution, etc. for treatment. 2. urticaria: arm itch after scratching the small bumps, and bumps into a wind and (or) angioedema, and accompanied by itching, generally caused by urticaria, you can use cetirizine, loratadine, fexofenadine and other drugs for treatment. Itchy arms after scratching small bumps may have other reasons, it is recommended that patients seek medical attention in a timely manner, improve the examination to clarify the cause of the disease in the doctor’s guidance for standardized treatment, the use of drugs need to follow the doctor’s instructions, avoid self-medication.