Botulinum Toxin Type A for Trigeminal and Postherpetic Neuralgia: An Umbrella Review of Systematic Reviews

Background and Objective: Trigeminal neuralgia (TN) and postherpetic neuralgia (PHN) are severe peripheral neuropathic pain conditions associated with substantial functional impairment. Although pharmacological treatments are available, many patients experience insufficient efficacy or poor tolerability. Botulinum toxin type A (BoNT-A) has emerged as a potential treatment, but uncertainties remain regarding its efficacy, safety, and clinical positioning. This umbrella review aimed to synthesise evidence from systematic reviews evaluating BoNT-A in TN and PHN. Methods: A systematic search was conducted in MEDLINE, Embase, Cochrane Library, Web of Science, and CINAHL from inception to November 2025. Systematic reviews with or without meta-analysis evaluating BoNT-A in adults with TN or PHN were included. Methodological quality was assessed using AMSTAR-2, and only moderate- or high-quality reviews were included. Primary outcomes were pain intensity reduction and responder rates (≥ 50% pain reduction). Secondary outcomes included quality of life and adverse events. Results: Ten systematic reviews (2015–2024) met the inclusion criteria. Botulinum toxin type A was consistently associated with reductions in pain intensity and higher responder rates than placebo, particularly in TN. In PHN, evidence was more limited but supported short-term (1–3 months) improvements in pain intensity. Evidence on quality of life was scarce and inconclusive. Botulinum toxin type A was well tolerated, with mostly mild and transient adverse events. Conclusions: Botulinum toxin type A appears to provide short-term pain relief in selected patients with TN and PHN and is generally well tolerated. Current evidence supports its role as an adjunctive third-line option for focal peripheral neuropathic pain, although heterogeneity and limited long-term data warrant cautious interpretation.