The bend of the legs generally refers to the popliteal fossa, if the blisters here are generally caused by contact dermatitis, eczema, papular urticaria, the treatment method has general treatment, drug treatment, etc.. 1. Contact dermatitis: lesions are mostly confined to the contact area, typical lesions for the border is clear erythema, on which there are pimples and papules, need to clean the lesions in time, avoid contact with suspected sensitizers, oral antihistamines such as chlortetracycline and so on. 2. Eczema: acute eczema is often manifested as erythema on the basis of the pinpoint to millet size pimples, papules, severe cases can appear small blisters, can be treated with topical glucocorticosteroids such as mometasone furoate. 3. papular urticaria: rash to the trunk, limb extension is common, group or scattered. At the beginning of the micro red papules, followed by mung bean or peanut size slightly fusiform red doughnut-like damage, often with small blisters at the top. It can be treated with topical glucocorticosteroids such as mometasone furoate. Blisters on the bend of the legs should be timely consultation, under the guidance of the doctor, do not use drugs without authorization.