Making scents: improvement of olfactory profile after botulinum toxin-A treatment in healthy individuals.

BACKGROUND: The axilla is particularly associated with body odor and putative pheromone production in humans. Although botulinum toxin type A (BT-A) is injected increasingly into the axillary skin to stop excessive sweating, its potential to control body odor is largely unexplored.

OBJECTIVE: The objective was to measure the impact of BT-A on human axillary odor in an objective and reproducible fashion.

METHODS: This study was a randomized, double-blind, placebo-controlled trial with 51 healthy volunteers receiving 50 U of BOTOX (Allergan, Inc.) in one axilla and placebo in the other. Odor quality was assessed by treated subjects (questionnaire) as well as by independent raters who were exposed to blinded T-shirt samples.

RESULTS: No major side effects occurred, and no subject withdrew from the study for medical reasons. Samples from the BT-A-treated side smelled less intense (p<.001) and better (p<.001) according to self-assessments. Likewise, independent raters found the BT-A-treated samples to smell less intense and better (p<.001). They preferred "to work together with the respective person" and found the odor "more erotic" (p<.001).

CONCLUSION: Side-by-side comparison of odor samples (T-shirt sniff test) by independent raters showed that axillary odor in healthy individuals is significantly more appealing after BT-A injection.