Several small red dots on the arm of the needle tip size may be related to papular urticaria, allergic purpura, etc., papular urticaria need to use antihistamines for treatment, and allergic purpura in addition to the need to use antihistamines for treatment, if necessary, can also be accompanied by a certain dose of vitamin C tablets and rutin tablets. 1. papular urticaria: belonging to the allergic skin disease, the clinical manifestation of scattered, small blisters at the top of the small pimples, surrounded by a red halo, often accompanied by itching symptoms, the onset of early patients can appear on the arm of several small red dots the size of a needle tip. Patients can usually apply antihistamines for treatment, such as loratadine, cetirizine and so on. 2. Anaphylactic purpura: Anaphylactic purpura can cause subcutaneous pinpoint hemorrhages, mainly manifested as submucosal hemorrhages, therefore, the patient can appear on the arm of several small red dots of the size of a pinpoint. Antihistamines, such as loratadine and cetirizine, can usually be used, along with a dose of vitamin C and rutin tablets if necessary. There are other causes of several small red dots the size of a needle tip on the arm (such as hemangioma), it is recommended that the patient go to the hospital in time to find out the cause of the disease, and then standardized treatment, so as not to delay the condition.