Small red spots on the skin are considered to be caused by folliculitis, eczema, and allergic purpura. 1. Folliculitis: a purulent inflammation confined to the mouth of the hair follicle, often caused by high temperatures, excessive sweating, poor hygiene habits. The lesions begin as red follicular papules and develop into pustules with a red halo around them. 2. Eczema: a true epidermal inflammation caused by a variety of internal and external factors, usually manifested as inflammatory papules, papules, the appearance of red spots and erythema, accompanied by varying degrees of itching symptoms. 3. Anaphylactic purpura: vascular allergic inflammation caused by bacteria, viruses, drugs and other causes. It occurs in the lower limbs, mainly in the extension of the calf, and in severe cases, it can spread to the upper limbs and trunk. Before the onset of the disease, there are often upper respiratory tract infection, low fever, general malaise and other prodromal symptoms, followed by the appearance of red papules, petechiae, ecchymosis and other manifestations. If small red spots appear on the skin, please do not judge and use medication on your own, but go to the hospital in time, and carry out standardized treatment after the cause of the disease is clarified.