To assess the real-world efficacy and safety of botulinum toxin type A (BTX-A) injection as a minimally invasive therapeutic alternative for chronic anal fissures and to identify factors associated with early treatment success.

We conducted a retrospective observational study including all patients aged ≥18 years with chronic anal fissure treated with BTX-A in a proctology outpatient clinic between January 2021 and September 2024, with a minimum follow-up of 12 months. Patients with inflammatory bowel disease were excluded. A standardized dose of 20 IU of BTX-A divided into two injections was administered in all cases. Primary outcomes were healing rate, number of treatment sessions required, recurrence, and procedure-related complications. The impact of optimized peri-procedural medical therapy (topical treatment and constipation control) on treatment response was also evaluated.

Twenty-two patients were included (54.5% male). Complete fissure healing was achieved in 64% after a single BTX-A session and in the remaining 36% after a second session, resulting in a 100% overall healing rate with no recurrences at 1-year follow-up. Patients with optimized peri-procedural medical therapy (n=16, 73%) showed a significantly higher early success rate, as all healed after one session (p<0.001). Only one case of transient mild fecal incontinence (4.5%) was observed, with no permanent sequelae. Complex fissure patterns (combined anterior and posterior fissures and fissure with anal ulcer) were exclusively identified among patients requiring two sessions.

In this real-world cohort, BTX-A injection demonstrated excellent efficacy and an outstanding safety profile for the treatment of chronic anal fissures, achieving universal healing with minimal morbidity. Optimized peri-procedural medical therapy emerged as a key modifiable factor for early success, significantly reducing the need for repeated interventions. These data strongly support BTX-A as a first-line, sphincter-preserving, minimally invasive alternative to lateral internal sphincterotomy, with the potential to change current therapeutic paradigms.