Acute Lower Back Pain after Intralesional Injection of Collagenase

The safety label for collagenase Data on all men undergoing collagenase injections for Peyronie's disease at our institution from October 2015 through December 2020 were retrospectively assessed. The study included 330 patients, 300 completing at least 1 full course (8 injections). Measured outcomes included incidence and timing of back pain, and associations with demographics and comorbidities. Of 330 patients, 19 (5.8%) experienced at least 1 episode of postinjection acute lower back pain. Of 300 who completed at least 1 full course of 8 injections, 4 (1.3%) reported back pain within the 8-injection course. A subset underwent additional rounds (16 or 24 injections). Back pain increased to 8.7% (13/149) during a second round, 6.9% (3/43) during a third. No association was found with age, diabetes or back pain history. Most cases occurred shortly after injection; all were self-limited or resolved with a single dose of ketorolac. This single-center, retrospective analysis suggests that intralesional collagenase injections for Peyronie's disease may cause acute lower back pain in up to 6% of patients. Patients may benefit from counseling regarding this risk. Incidence rises with additional rounds of treatment. Prospective safety data regarding >8 injections do not exist. No patient had long-term sequelae of back pain.