Redness in the ear may be caused by acute otitis externa, eczema of the ear canal, boils of the external ear canal, etc. 1. Acute otitis externa: when infected by bacteria, patients will have redness in the ear, and patients mainly manifest symptoms such as congestion and swelling of the skin of the external auditory canal, pain, and severe patients will have hearing loss. 2. Eczema of the ear canal: generally related to allergic reactions, mostly due to allergic factors leading to localized inflammatory lesions in the ear canal, resulting in redness, roughness, itching and other symptoms of the skin of the ear canal, and sometimes there will be oozing fluid. 3. Acute external auditory canal boils: External auditory canal boils occur in the cartilaginous part of the external auditory canal, where the skin contains hair follicles, sebaceous glands and ceruminous glands, and bacteria invade these skin attachments and form abscesses due to infection. Localized redness, swelling and pain may appear at the beginning of the disease. It is recommended that the patient go to a regular hospital in time, under the diagnosis of the doctor, according to the patient’s specific situation, to take targeted treatment.