Redness and itching outside the ears are commonly caused by localized skin allergies. Allergens need to be checked and then kept away from. Local desensitizing ointment can be applied, for example, hydrocortisone can be used. If the symptoms are more serious, you can take oral anti-allergy medication and try not to stimulate the local skin to cause infection. In addition to itching and redness of the external ear canal, there is also yellow discharge, which is considered to be caused by eczema infection of the external ear canal, and is also related to allergy. There are also infections and low immunity of the body can occur. You can use Euthyrox topical application, and if there are signs of infection, you can mix Bactrim with the joint application. If the symptoms are recurring, you can use drugs to regulate the body’s immunity.