Erythema on the calf and itching, common causes are insect bite dermatitis, contact dermatitis, venous stasis dermatitis. 1. Insect bite dermatitis: insect bites lead to allergic reactions of the calf skin, erythema and itching, treatment can be applied locally to stop itching agents such as glycerine lotion. 2. Contact dermatitis: if you are allergic to the clothes you wear, or allergic to certain topical drugs, it will lead to erythema and itching. Contact with the allergic substances should be stopped, and can be taken orally levocetirizine hydrochloride tablets anti-allergy treatment. 3. Venous stasis dermatitis: If you suffer from varicose veins, poor blood return will lead to stasis dermatitis on the surface of the skin due to lack of oxygen and ischemia, presenting erythema, hyperpigmentation, flaking with itching. If the above factors exist, it is necessary to consult a doctor in time to identify the specific cause and follow the doctor’s instructions.