The evaluation of underarm deodorants

Synopsis Double-blind cross-over trials in which trained assessors evaluated axillary malodour on a 0 to 10 scale showed that ethanol at 60% and 99% w/w significantly reduced odour for up to 24 h. Reduction in odour was increased by the addition of non-volatile antimicrobial ingredients such as chlorhexidine, Irgasan DP 300 (Triclosan, Ciba Geigy) or aluminium chlorhydrate. Volunteer panellists were able to identify statistically significant deodorant effects when they rated their own axillary odour on a 0 to 10 scale. An odour absorber, zinc ricinoleate (Grillocin, Grillo-Werke, A. G.) was used to treat existing malodour and gave reduced perception of that malodour for up to 24 h. A close correlation was found between panel odour scores and the bacterial status of the axilla as assessed by the replipad technique when biocidal systems were studied. Irgasan DP 300, a bacteriostat, did not perform so well in skin flora sampling procedures, but was nevertheless effective as a deodorant ingredient. Thus in vivo microbiological techniques, although often useful as predictors of deodorancy, do not replace the carefully controlled clinical trial with direct assessment of odour.