What it is
AbobotulinumtoxinA is the generic name for a medicine sold in the United States as Dysport. It is a type of botulinum toxin type A. It is a protein made by a germ called Clostridium botulinum. The protein is cleaned up and freeze-dried. A clinician gives it as a shot into a muscle.
In the muscle, it blocks the signal that tells the muscle to tighten. The muscle relaxes for a few months. Then it slowly works again as the nerve endings grow new links. The FDA label covers three uses. Two are nerve and muscle problems: neck muscle spasms (neck dystonia) and muscle stiffness (spasticity). One is cosmetic: frown lines between the eyebrows.
The strength is measured in Units. The label says Dysport Units belong to this product only. They cannot be compared with, or changed 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 started in Britain. In the 1980s, a government lab at Porton Down made its own cleaned-up type A toxin. It worked with a company called Porton International. It also worked with UK doctors trained by Alan Scott, an American toxin pioneer. The name is usually thought to mix “dystonia” and “Porton”. Europe first approved it in December 1990. At first it was used for eyelid spasm and face spasm.
Later, the French company Ipsen bought the business. Ipsen still makes the product today. In 2007, Ipsen teamed up with Galderma for cosmetic uses. The FDA first approved Dysport in April 2009. That was for neck dystonia and frown lines. Over the next ten years, the FDA added muscle stiffness 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 was tested in its own trials against a dummy treatment (placebo). In neck dystonia, two trials included 252 people who had never had a toxin shot. They got one dose or placebo. Four weeks later, the Dysport groups had bigger gains on a standard neck dystonia score. For frown lines, three trials looked at day 30. In those trials, 52 to 60 percent of people on the product reached “none” or “mild” lines. This was based on ratings by both the clinician and the person. No one on placebo reached that.
The muscle stiffness trials included adults after a stroke or brain injury. They also included children with cerebral palsy. Muscle stiffness went down a few weeks after the shot. But not every measure improved. In the trial of children’s arms, doctors’ overall ratings were not clearly different from the low-dose comparison group. The boxed warning (the FDA’s strongest warning) applies to every use.
Dysport is also being tested for preventing migraine, which is not an approved use: in July 2026 Ipsen said two large Phase 3 trials with 1,510 patients in total, one in episodic and one in chronic migraine, both met their main goal of fewer migraine days a month at week 24 than placebo, but no figures have been published and no approval has been requested.
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.
Migraine prevention is under investigation and is not an approved indication: two Ipsen-sponsored Phase III placebo-controlled trials with extension phases, NCT06047457 (episodic migraine, n = 751) and NCT06047444 (chronic migraine, n = 759), both met their primary endpoint of change from baseline in monthly migraine days at week 24 (weeks 21 to 24) versus placebo according to the sponsor’s topline announcement of 9 July 2026, which reported no new safety signals and disclosed no effect sizes, dose levels or filing timeline.
Regulatory picture
In the United States, the only FDA-approved product with abobotulinumtoxinA is Dysport. Ipsen holds the license. Galderma sells it for the cosmetic use. The same toxin is sold in other countries under other names, such as Azzalure in Europe. Those versions are not FDA-approved. Botulinum toxin products with only a foreign license, sold for import or online, are also not FDA-approved.
In April 2024, the FDA warned that fake botulinum toxin had reached patients in several states. In November 2025, the FDA announced 18 warning letters to websites. These sites were selling unapproved and wrongly labeled botulinum toxin products. Pharmacies cannot make their own copies (compounding) of 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.
