The common causes of many small red dots on the body include allergic purpura, keratosis pilaris and so on. 1. allergic purpura: the etiology of this disease is complex, bacteria, viruses, food, drugs and so on can lead to the onset of malignant tumors and organs of non-specific autoimmune disease may also be the cause of the disease. Predominantly in the lower limbs, to the calf extensor side is common, skin lesions manifested as red papules, purpura, ecchymosis and other symptoms. 2. Keratosis pilaris: the etiology and pathogenesis of this disease is unknown, may be related to autosomal dominant inheritance, vitamin A deficiency, metabolic disorders and other factors. It is characterized by red follicular papules of the size of a needle tip to a grain of corn, accompanied by erythema, hyperpigmentation and other symptoms. It is recommended that patients who find small red spots on the body, can not subside on their own, should promptly go to the regular hospital dermatology department, follow the doctor’s instructions for a clear diagnosis, reasonable treatment, to avoid delaying the condition.