Allergy due to topical medications in chronic otitis externa and chronic otitis media.

Thirty-four patients suffering from chronic otorrhoea were tested for delayed type contact allergy. Patch testing showed a relevant positive reaction in 19 patients (56%). The most frequent allergens were aminoglycosides with neomycin and framycetin as major offenders. Other antimicrobial agents (clioquinol, polymyxin B), cream bases (lanolin) and corticosteroids (tixocortol) were less common allergens encountered. These results indicate that it is almost obligatory to perform patch testing in any patient with long-standing otitis which does not respond to local therapy. Scoring of the patch tests has to be extended to 7 days, as notably the aminoglycosides and corticosteroids only become positive after such a long interval. Because of the high risk of sensitization, topical preparations containing neomycin and framycetin should not be used routinely. We recommend the use of either a topical antiseptic or a topical antibiotic with low allergenic potential for the initial treatment of otorrhoea.