Scientists in the US published their study in the Journal of Cosmetic Dermatology in which they compared the efficacy of two aluminium salt solutions in a sweating simulation.
They found that the topical treatment containing 20% aluminium chloride hexahydrate quantitatively reduced sweat more effectively than the one with 1% aluminium acetate when analysed on filter paper, although the subjects themselves found equivalent efficacy for both.
Overall, the study suggests that not all topical antiperspirant solutions for treatment of sweating are equally effective; and that the simple, low cost method used for quantitatively comparing the efficacy of locally applied antiperspirants was also effective.
As there is a lack of studies objectively comparing the efficacy of topical antiperspirants in reducing sweat, the research team set up a subject, rater, and statistician-blinded, randomized, controlled trial.
In it, 19 subjects were exposed to a standardized heat challenge for 3 hours in which the two topical agents (A = 20% aluminum chloride hexahydrate, B = 1% aluminum acetate) were applied in opposing underarms.
A sauna suit induced sweating during three 30-min heat intervals: one before the study agents; then with both study agents, one on each side; and finally after the agents were washed off.
Sweat levels were measured by securing Whatman filter paper to each underarm and measuring the paper weight after each heat interval. The difference in paper weight following each heat interval between Study Agent A and Study Agent B was measured by a gravimetric scale.
The test found that Topical agent A, containing the aluminium chloride, had a significantly greater effect at reducing axillary sweating than B.
The scientists do admit though that the exact reason for this is unclear, as it may be that more concentrated salt solutions are consistently more effective, given the difference in molecular weights of the two formulations, with A significantly higher than B.
The reason these exact concentrations were used in this study is because the products were commonly used and were commercially available.
To account for the difference, the researchers say that the study may be reconfigured with a higher concentration aluminium acetate solution, and that it would also be logical to assess local irritation from the antiperspirant solution, as use of more concentrated solutions may be limited by local irritant contact dermatitis.