Many small red dots on the back of the feet are considered to have the following possibilities: 1. Allergic purpura: small red dots do not protrude from the skin surface, in the state of petechiae, petechiae, pressure does not fade, the rash is symmetrically distributed, no blood blisters, rupture, etc., at the same time can be accompanied by pain and swelling of the ankle joint. The disease is mainly caused by infection or drug factors, or allergic factors. You can take oral vitamin C capsules, rutin tablets, and topical glyburide lotion for treatment. For arthralgia, you can take oral tretinoin tablets for treatment; 2. Eczema: It may be an allergic reaction caused by wearing rubber or plastic slippers, and the rash is often well-defined. You can take levocetirizine hydrochloride capsules orally and apply hydrocortisone butyrate ointment topically for treatment.