Red spots on legs are usually due to purpura, eczema, allergies, insect bite dermatitis, contact dermatitis and other causes. 1. Allergic purpura: Bruises and petechiae on the skin caused by drugs and viral infections, mainly on the legs, but also on other parts of the body. 2. Eczema: Eczema appears on the skin due to hot and cold stimulation, chemical stimulation and exercise. It usually manifests as red spots on the legs, some of which may merge into fragments, with dry and rough skin accompanied by itching. 3. Insect bite dermatitis: mosquitoes are more common in summer, after being bitten by mosquitoes, red spots may appear on the legs. 4. Contact dermatitis: if the patient has contact dermatitis, mostly due to contact with certain exogenous substances, in addition to red spots on the legs, but also accompanied by itching symptoms. Red spots on the legs may also be caused by cherry-like hemangioma, should be timely to the hospital, under the guidance of the doctor to clarify the cause of standardized treatment.