[Off-label type A botulinum toxin in the treatment of non-spastic pain: a narrative review]

Botulinum toxin is a drug whose potential analgesic effect has attracted increasing interest. However, its use for pain treatment is not included in the approved indications in Spain, and the evidence is heterogeneous across different clinical conditions. The aim of this narrative review was to analyze the current evidence on its off-label use in different pain syndromes, assessing its level of evidence, efficacy and safety. A separate literature search was conducted for each condition, prioritizing systematic reviews, meta-analyses, and clinical trials, particularly the most recent ones. The available evidence is growing, although it is limited by the heterogeneity of the conditions and methodologies, small sample sizes, and the scarcity of comparative studies against standard treatments. Currently, it cannot be recommended as a first-line treatment for any painful condition, but it could be considered as an alternative in selected patients with certain neuropathic pain conditions, piriformis syndrome, plantar fasciitis, and epicondylitis. Its safety profile is favorable, with a low incidence of adverse effects. The lack of superiority over some therapeutic alternatives limits its widespread use. Higher-quality studies with standardized protocols are needed to establish robust clinical recommendations.