Otitis externa is an infection of the external ear canal (not a true upper respiratory tract infection). It may be caused by a viral, bacterial or fungal infection, a complication of a skin condition (e.g. eczema) or a foreign body. Otitis externa may complicate chronic suppurative otitis externa as the draining pus irritates the skin of the external canal.

• With mild otitis externa the ear is itchy but the external canal appears normal.
• With moderate otitis externa the ear is painful with a purulent, smelly discharge. The pain is worse if the pinna (external ear) is pulled. On examination the external canal is red and contains debris. Partial obstruction of the external ear canal may cause mild deafness.
• With severe otitis externa the ear is very painful with deafness due to complete obstruction of the canal. On examination the external canal is red and swollen.

A boil in the external canal or mumps may also present with earache.