I had been told that adding local to botulinum toxin might block receptors that pick up the agent and hence decrease its effectiveness. A study using saline only and lidocaine- botulinum combo found no difference.
J Eur Acad Dermatol Venereol. 2012 Mar;26(3):314-8.
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.
Güleç AT abstract here
- “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.”
- equal in onset, effectiveness and duration of decreased sweating
- Injection the lidocaine group was considered less painful