Ear red clinically, generally seen in the following cases: a. Allergic reactions, that is, local skin allergies caused by, for example, the auricular skin for infrequently used hair dye, apply sunscreen, cosmetics, appear the entire auricular contact cosmetics location appear skin redness, swelling, itching. Second, mosquito bites, sometimes can not provide a clear medical history, but can see the local skin, there is a bite of the needle eye, is the mosquito bite appeared local skin redness, itching, and even edema reaction. Third, acute chondromalacia of the auricle is red, swollen, and painful, but has not yet reached the manifestation of suppuration. Fourth, the infection alone is an acute infection of the skin of the auricle, showing a red rash with clear borders and sensitivity to penicillin.