The appearance of small red dots on the body may be caused by eczema, allergic purpura, contact dermatitis and other diseases. 1. Eczema: the etiology and pathogenesis of eczema are not yet completely clear, and may be related to a variety of factors such as internal and external causes. Eczema can be manifested as erythema, papules, blisters, etc., and there will also be vesicles, oozing, accompanied by itching. 2. Anaphylactic purpura: The pathogenesis and etiology of anaphylactic purpura are not yet clear, and may be caused by a variety of factors, such as food, drugs, infection, etc. The patient will have purplish purpura. Patients will have purple-red purpura, and may also have arthralgia, abdominal pain and other symptoms. 3. Contact dermatitis: contact dermatitis is mainly an allergic reaction caused by skin contact with sensitizers, manifested as erythema, papules and so on. Patients appear on the body appeared small red dots, may be urticaria, idiopathic thrombocytopenic purpura and other diseases caused by, should consult a doctor in a timely manner, in accordance with the doctor’s instructions for treatment.