What it is
AbobotulinumtoxinA is the generic name of the botulinum toxin type A product sold in the United States as Dysport. Like the other members of this family, it is a protein made by the bacterium Clostridium botulinum, purified and freeze-dried, and given by a clinician as an injection into a muscle.
Once in the muscle, it blocks the chemical message that tells the muscle to contract. The muscle relaxes for a period of months and then recovers as nerve endings rebuild their connections. The FDA label covers two neurological uses, neck dystonia and spasticity, and one cosmetic one, frown lines between the eyebrows.
Strength is measured in Units, and the label is explicit that Dysport Units belong to this product alone. They cannot be compared with, or converted into, the Units of any other botulinum toxin product.
AbobotulinumtoxinA is a purified botulinum neurotoxin type A complex produced by fermentation of Clostridium botulinum type A, Hall strain, and purified from culture supernatant by precipitation, dialysis and chromatography. The label describes the complex as the neurotoxin plus haemagglutinin proteins and non-toxin non-haemagglutinin protein. The formulation contains human serum albumin and lactose and may carry trace cow’s milk protein, hence the labelled contraindication in cow’s milk allergy.
The active 150 kDa dichain neurotoxin follows the type A sequence of events set out in the label: heavy-chain binding to receptors on cholinergic nerve terminals, receptor-mediated endocytosis, pH-induced translocation of the light chain into the cytosol, and zinc-dependent cleavage of SNAP-25, which blocks acetylcholine exocytosis at the neuromuscular junction. Transmission returns as the junction recovers from SNAP-25 cleavage and new nerve endings form. The label states that the product cannot be detected in peripheral blood after intramuscular injection at recommended doses. Potency is assigned with a cell-based assay against a product-specific reference standard.
Who made it and when
Dysport has British roots. In the 1980s the government’s Centre for Applied Microbiology and Research at Porton Down, working with the company Porton International and with UK doctors trained by the American toxin pioneer Alan Scott, developed its own purified type A toxin. The name is usually read as a blend of “dystonia” and “Porton”. It was first approved in Europe in December 1990, initially for eyelid spasm and facial spasm.
The French company Ipsen later bought the business and manufactures the product today. In 2007 Ipsen partnered with Galderma on aesthetic uses. The FDA first approved Dysport in April 2009, for neck dystonia and for frown lines, and over the following decade added spasticity in adults and in children.
CAMR produced its type A toxin by a process distinct from the Schantz method behind the American product, building on 1980s vaccine-production work; Porton International, formed in 1984 in partnership with CAMR, commercialised it. Ipsen acquired Porton International’s successor and manufactures the product. Outside the US its potency has historically been expressed in Speywood units, a reminder that its assay has always been its own. An aesthetic presentation launched in Germany in 2006 and was authorised in Europe in 2009 as Azzalure, distributed by Galderma.
In the United States, BLA 125274 was approved on 29 April 2009 for cervical dystonia in adults and glabellar lines in adults under 65. Supplements added adult upper limb spasticity (July 2015), paediatric lower limb spasticity from 2 years of age (29 July 2016), adult lower limb spasticity (June 2017) and paediatric upper limb spasticity from 2 years (September 2019). That last approval first excluded cerebral palsy because of another product’s orphan-drug exclusivity; a 2020 labelling change, after the two manufacturers waived their respective orphan exclusivities, removed the exclusion. The current label reads “spasticity in patients 2 years of age and older”.
What the data say
Each approved use rests on its own placebo-controlled trials. In neck dystonia, two trials in 252 people who had never had a toxin tested a single dose against placebo and reported larger improvements on a standard dystonia rating scale four weeks later. For frown lines, three trials reported that 52 to 60 percent of people given the product reached “none” or “mild” on a combined clinician-and-participant rating at day 30, against none on placebo.
The spasticity trials enrolled adults after stroke or brain injury and children with cerebral palsy, and reported reduced muscle stiffness a few weeks after injection. Not every measure moved: in the children’s arm trial, clinicians’ overall ratings did not differ significantly from the low-dose comparison group. The boxed warning applies across every indication.
Cervical dystonia: two randomised double-blind single-dose studies (121 active, 131 placebo) of 500 Units intramuscularly reported TWSTRS total-score treatment differences at week 4 of −8.9 (95% CI −12.9 to −4.7) and −5.9 (−10.6 to −1.3). Glabellar lines: 50 Units in five 10-Unit aliquots gave composite 2-grade responder rates at day 30 of 55%, 52% and 60% in GL-1, GL-2 and GL-3, versus 0% on placebo.
Adult upper limb spasticity (NCT01313299): least-squares mean MAS change in the primary targeted muscle group at week 4 was −1.2 (500 U) and −1.4 (1000 U) versus −0.3, with Physician Global Assessment also favouring active treatment. Adult lower limb (NCT01249404): ankle MAS change −0.8 at 1500 U (significant) and −0.6 at 1000 U versus −0.5. Paediatric lower limb (NCT01249417): −0.9 and −1.0 at 10 and 15 U/kg/leg versus −0.5 at week 4. Paediatric upper limb (NCT02106351, low-dose-controlled): −2.0 and −2.3 at 8 and 16 U/kg versus −1.6 at 2 U/kg at week 6, with non-significant PGA differences. Neutralising antibody formation is a recognised limitation of repeated botulinum toxin exposure.
Regulatory picture
In the United States the FDA-approved product containing abobotulinumtoxinA is Dysport, licensed to Ipsen, with Galderma marketing it for the cosmetic indication. Nothing else containing this molecule is approved here. The same toxin is sold in other countries under other names, such as Azzalure in Europe, and those versions are not FDA-approved products. More broadly, botulinum toxin products that hold only a foreign licence and are offered for import or online sale are not FDA-approved.
The FDA warned in April 2024 that counterfeit botulinum toxin had reached patients in several states, and in November 2025 it announced 18 warning letters to websites selling unapproved and misbranded botulinum toxin products. Pharmacy compounding does not apply to a licensed biologic like this one.
AbobotulinumtoxinA is licensed under BLA 125274 (Ipsen Biopharm Ltd) under section 351 of the Public Health Service Act. Biological products of this kind fall outside the 503A bulk drug substances framework and there is no lawful route for a pharmacy to compound a copy, so the compounding field is recorded as not applicable rather than restricted. The label carries a boxed warning for distant spread of toxin effect and states that Dysport potency Units cannot be compared to or converted into those of any other botulinum toxin product.
Botulinum toxin products marketed in the US without an FDA licence are unapproved new drugs and misbranded under the FD&C Act. The April 2024 alert concerned counterfeit product bearing Botox branding, and CDC linked counterfeit or mishandled injections to illness in several states. In the November 2025 warning letters, FDA stated that although FDA-approved botulinum toxin products are on the US market, no approved application covered the products the named websites offered. None of these actions concern licensed Dysport itself; they mark the line between the licensed product and unlicensed or counterfeit product.
