The running water behind the ear scabs are considered to be caused by eczema behind the ear, contact dermatitis and other diseases. 1. Eczema behind the ear: refers to the allergic polymorphic dermatitis caused by a variety of factors. Often due to allergies, may appear millet size papules or small blisters, lesions border is not clear, often due to scratching pitting vesicles, and accompanied by obvious plasma oozing. Performance for the local skin itching, running water, running water after the crust. 2. Contact dermatitis: contact dermatitis can also cause running water and scab behind the ear, when the ear after contact with certain substances, can make the ear and other parts of the inflammatory reaction, after the ear can appear erythema, edema, and can be accompanied by blisters or oozing, blisters rupture, vesicles or scabs can be formed. The person who has running water and scabs behind the ear should go to the hospital in time, after clarifying the cause of the disease, and receive treatment as soon as possible.