Dysport recently received approval for medical and cosmetic use in the United States. Although it is new here, it has been used for a number of years outside of the US, and the medicine is 18 years old.
There are some differences between Botox and Dysport even though they are both forms of botulinum toxin A. The molecule of Dysport is smaller in size than that of Botox. This may account for the observation that Dysport spreads farther in the skin after it is injected. Also, more units of Dysport are needed per injection than Botox to achieve the same desired result. The company that distributes Dysport recommends a conversion ratio of 2.5 units of Dysport for every 1 unit of Botox.
Another difference between the two products may be in how long their effect lasts. One study comparing Dysport to Botox found that Botox seemed to last longer.
A separate issue is the potential to develop proteins against these products called antibodies. Proteins against Botox have been reported which may account for the observation that some people become resistant to treatment over time. The US distributor of Dysport reports that no antibodies developed in patients receiving Dysport in clinical trials even after 9 treatments.
What these differences mean in the real world remains to be seen and will probably be discovered after a few months of use. Medicis, the distributor of Dysport, expects to begin supplying Dysport mid-July. The exact date of distribution will depend on how quickly the medicine passes through customs since it is being imported.