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1% clotrimazole more effective than 3% boric acid in alcohol for otomycosis: randomised trial

March 27 2017

In a randomised controlled trial 1% clotrimazole solution has been found to tbe more effective at treating otomycosis than its cheaper alternative, 3 per cent boric acid in 70 per cent isoproypyl alcohol. Otomycosis is a worldwide superficial fungal infection of the external auditory canal and auricle which is more prevalent in tropical zones.

Dr Romsaithong and colleagues compared 1 per cent clotrimazole solution with 3 per cent boric acid in 70 per cent alcohol  at Khon Kaen Hospital, Thailand, where otomycosis has been reported in 11 per cent of patients presenting with inflammatory conditions of the ear canal. The trial was double-blind, controlled and randomised, trial and patients  patients’ ear canals were examined under the operating microscope one week after a single application of the treatment. Their condition was either classified as cured or not cured, based on the presence or absence of fungus.


A typical and appearance of severe otitis externa, showing much debris, which requires removal.

The cure rate for the clotrimazole group was significantly higher with 85.2%, compared to 67.3% for the boric acid group, giving an absolute difference of 17.9% (p = 0.028). The results of this study concurred with similar previous controlled trials.

The secondary outcome of the study revealed that patients treated with clotrimazole also reported fewer adverse events. While this study lacked long-term follow up of treatments, it was evident that a single application of 1 % clotrimazole solution is both more effective at treating otomycosis and less irritating than 3% boric acid in 70 per cent alcohol.

Article: Romsaithong et al 2016.