Conversion ratio between Dysport and Botox in clinical practice: an overview of available evidence

The optimal conversion ratio between Dysport and Botox—the two botulinum neurotoxin type A products (BoNT-As) supported by the larger bulk of evidence—has been extensively debated, because of its broad medical and economic implications. The article discusses the available evidence on the conversion ratio between Dysport and Botox in adults affected by spasticity, cervical dystonia, blepharospasm and hemifacial spasm, with a focus on clinical trials that specifically addressed this issue. In addition, some suggestions on the conversion ratio between Dysport and Xeomin can be extrapolated, since Xeomin has the same efficacy and safety profile as Botox and is exchangeable with Botox with a 1:1 conversion ratio. Taken together, the findings retrieved from this literature research suggest that a conversion ratio of 3:1 (Dysport:Botox)—or even lower—can be considered appropriate for the treatment of the above-mentioned conditions. Higher conversion ratios may lead to an overdosing of Dysport, with a potential increased incidence of adverse events. Therefore, we recommend that physicians using both products consider using a lower conversion factor as a guide, adjusting it upwards as required based on the specific characteristics and response to treatment of each patient.