Background  Botulinum toxin A (BTX-A) is an effective and safe treatment modality for primary axillary hyperhidrosis. However, some patients experience considerable pain during injections.

Design  Dilution of botulinum toxin A in lidocaine vs. in normal saline for the treatment of primary axillary hyperhidrosis: a double-blind, randomized, comparative preliminary study.

Objective  The aim of this study was to compare the efficacy, safety and pain tolerance of lidocaine-diluted BTX-A vs. saline-diluted BTX-A for the treatment of axillary hyperhidrosis.

Methods  Eight patients were injected with 50 U of BTX-A diluted in 0.5 mL of saline and 1 mL of 2% lidocaine into one axilla and 50 U of BTX-A diluted in 1.5 mL of saline into the other axilla in a randomized fashion. The pain associated with the injections were self-assessed by the subjects using a 100-mm visual analogue scale (VAS).

Results  Lidocaine-diluted BTX-A and saline-diluted BTX-A were similarly effective regarding the reduction in sweat production, the onset of sweat cessation and the duration of hypo/anhidrosis. Nevertheless, the pain VAS score during the injections was significantly lower in the axilla treated with lidocaine-diluted BTX-A than the one treated with saline-diluted toxin.

Limitations  Preliminary study due to relatively small sample size.

Conclusion  Botulinum toxin A diluted in lidocaine causes significantly less pain than BTX-A diluted in saline, whereas it is is equally effective and safe as the latter one in treating axillary hyperhidrosis. Therefore, we suggest that lidocaine-diluted BTX-A may be a better treatment option for the patients with primary axillary hyperhidrosis.