Pain sensation during intradermal injections of three different botulinum toxin preparations in different doses and dilutions.

Background: Pain sensation associated with injections of botulinum neurotoxin (BoNT) is commonly reported. To date differences in pain sensation between the commercially available products containing BoNT have not been quantified.

Objectives: The pain sensations during injection of Dysport, Botox, Neurobloc, and pure saline (control) were compared. In addition, the nociceptive effect of different volumes used for the dilution of the same BoNT dose was investigated.

Methods: In a prospective, double-blind, controlled trial, 10 healthy subjects were injected intradermally with Dysport (12 U), Botox (3 and 4 U), Neurobloc (150 and 300 U) reconstituted in 0.9% saline, and pure saline. Pain sensation was quantified during injections.

Results: Neurobloc injections caused significantly more injection pain than Botox, Dysport, and saline. No significant differences between Dysport, Botox, and saline were found, although there was a trend toward less pain with pure saline injections. Higher pain levels with higher volumes could not be demonstrated significantly.

Conclusion: Our data demonstrate that BoNT type B injections are associated with substantial pain. There is a considerable difference between the commercially available BoNT type B compared to the two BoNT type A preparations. Therefore, considering mitigation of injection pain seems necessary when using BoNT type B.