The appearance of many red dots on the feet without pain, it is possible that the patient has allergic dermatitis, allergic dermatitis may occur due to allergic food, or allergic pollen particles and other factors to stimulate the body, resulting in local metaplastic inflammation, due to individual differences, some people appear small red dots without obvious itching symptoms, and does not produce pain, but the lesions are real, red dots actually The main manifestation is an inflammatory papule or papule. The red dots may also be a patient with allergic purpura. The process of allergic purpura occurs mainly due to allergic factors that cause the skin capillaries to produce dysfunction and eventually form a certain bleeding reaction.