The appearance of small red spots on the body may be caused by allergies, and may also be caused by other diseases such as infectious diseases, which need to be specifically analyzed. 1. Allergy: patients in contact with certain allergens such as drugs, food, etc., the skin will appear a large erythematous papules, wind, etc., accompanied by a strong sense of itching, the need for timely anti-allergy treatment. 2. Infectious diseases: If the patient has erythematous papules all over the body, and there is no obvious itching, accompanied by fever, then consider that the patient is infected with some kind of germs, such as rubella, scarlet fever, measles and other diseases. The appearance of small red spots on the body may also be due to skin purpura, spider nevus and other diseases, based on the symptoms of small red spots can not accurately determine the cause, it is recommended that the patient go to the hospital in a timely manner, combined with the history and results of the examination to make an accurate judgment, under the guidance of the doctor to clarify the cause of the symptoms of the treatment.