Small pimples broke out on the back of the hand.

Hello, this is usually an allergic reaction caused by local bacterial skin infection or contact with allergens. It is usually necessary to avoid contact with allergens. It is recommended to go to the dermatological department for examination and consultation, and it is appropriate to treat according to the specific cause. It can usually be treated by relevant external drugs, and it is recommended to do so under the guidance of a professional doctor.