The causes of small red spots on the arms that itch are considered psoriasis and allergic skin diseases, as follows: 1. Psoriasis: psoriasis of the punctate type is considered. Psoriasis is a chronic, hereditary, inflammatory skin disease, before the onset of upper respiratory tract infection, and red papules, red spots on the arms, and covered with thick scales, accompanied by itching, after gently scraping off the above scales with your hands, you can see the phenomenon of bleeding. The company’s main business is to provide a wide range of products and services to the public. Red papules, erythema, accompanied by itching, serious cases will also appear blistering or peeling phenomenon, in the treatment of the first when going out, you need to apply sunscreen or isolation cream, if itching is serious, then you can take oral Orotadine hydrochloride tablets and fexofenadine hydrochloride tablets, in the external medicine can be applied to the mixture of mometasone furoate cream and urea vitamin E milk for external use. Therefore, for patients with small red dots on the arms with itching, it is recommended to go to a regular hospital and under the guidance of a dermatologist for the appropriate clinical treatment.