Effectiveness of Local Botulinum Toxin Injection for Perianal Pain after Hemorrhoidectomy.

: Hemorrhoidectomy is commonly associated with post-operative perianal pain. Local botulinum toxin injection by relaxing the smooth muscles of the perianal sphincter and reducing anal pressure can be effective in decreasing post-operative pain. This study evaluates the effectiveness of local botulinum toxin injection in controlling pain after hemorrhoidectomy. : This study was a double-blind, randomized clinical trial. A total of 40 patients undergoing hemorrhoidectomy who were referred to Shariati Hospital in 2019- 2020 were enrolled as participants and divided into two groups. In one group, injection of botulinum toxin was done in intersphincteric area, and in the other group, there was no intervention after hemorrhoidectomy. SPSS software version 24 was used to analyze the data. : Local botulinum toxin injection (MASPORT® 500) significantly reduced post-operative perianal pain on the first, third, fifth, and seventh days after the operation compared with the second group (<0.05). The mean pain scores in the first, third, fifth, and seventh days in the first and second groups were 7.60 (±0.88) versus 8.25 (±1.16), 40.5 (±0.88) versus 6.05 (±0.99), 2.45 (±0.51) versus 3.05 (±0.68), and 2.05 (±0.39) versus 1.70 (±0.57), respectively. Furthermore, pain during defecation was significantly lower for the experimental group (<0.05). : Local botulinum toxin injection effectively improves post-operative pain after hemorrhoidectomy. Further studies are needed to prove the clinical value of local botulinum toxin injection.