Red bags on the legs are particularly itchy, may be related to urticaria, contact dermatitis, mosquito bites and other reasons. 1. Urticaria: due to the expansion of small blood vessels in the skin of the legs and the increase in permeability caused by limited edema reaction, manifested as red red air masses of varying sizes, often accompanied by itching symptoms. 2. Contact dermatitis: if the legs are in contact with allergenic substances such as ointment, it can cause inflammatory reaction and skin damage, manifested as erythema, papules, and in severe cases, it can be manifested as erythema, blisters, blisters, often accompanied by itching symptoms. 3. Mosquito bites: when mosquitoes bite the skin on the legs, they can release certain acidic substances into the human body, which can cause local inflammatory reaction, localized redness, accompanied by itching. It is recommended that the legs have red bags especially itchy people go to the hospital in a timely manner, clear cause, under the guidance of the doctor for standardized treatment.