(OE) is inflammation of the external ear canal. It may be either localised (usually due to an infected hair follicle) or diffuse, in which case it may extend to the external ear and the tympanic membrane. Diffuse OE is also known as swimmer’s ear. There are many causes of OE including bacterial or fungal infections and dermatitis. Trauma, such as over-zealous cleaning, foreign objects (which include ear plugs and hearing aids) and ear syringing, is another potential cause, as are environmental factors such as high temperature or humidity, perspiration and swimming (particularly in polluted water). In some cases, no cause can be identified