Axillary pH and influence of deodorants

Background/aims: In moist intertriginous regions, such as the armpit, the p H value is physiologically higher than in other skin regions. The regulatio n of the axillary pH-value was examined in an open study with 48 subjects i n three groups with n=16 each. Methods: In the first 10 days (run-in) the s ubjects received a standard treatment in the axilla with shaving, cleansing and application of a pH-neutral deodorant. This was followed by a 5 day tr eatment period with the three test products (pH5 Eucerin(R) Deodorant Roll- on, Deodorant Balsam Spray, Deodorant cream). The study was concluded by a wash-out period with procedures identical to the run-in phase. The pH was m easured with a calibrated pH-meter. Results: A significant pH reduction was shown during the treatment period w hen compared to the run-in phase. The Deodorant Roll-on induced a reduction of the mean pH values from 6.1 to 5.3, the Deodorant Balsam Spray from 6.5 to 5.7 and the Deodorant Cream from 6.2 to 5.3. During the wash-out period all pH values returned to baseline. Conclusion: All of the deodorants tested demonstrated a significant reducti on in axillary pH. There is evidence that a high skin pH promotes the growt h of several microorganisms that produce malodor. Therefore, the regulation of pH may contribute to the deodorant efficacy of the test products.