Botox is the original wrinkle-buster. It relaxes the muscles where it is injected so they can’t form the folds in the skin that lead to wrinkles. Now Canadians have access to 2 more muscle relaxants: Xeomin and Dysport.

These 3 agents differ from each other in their composition, leading to differences in onset of action, ability to diffuse (move) through tissues and duration of action. As each new agent was introduced, there was confusion about how the dosage would need to be adjusted to give the same results as Botox.

This new study answers these questions. It is a well-designed study published in a peer-reviewed journal, The Journal of Plastic and Reconstructive Surgery.

They took 45 women and treated one side of the face with Botox and the other side with Xeomin. Both the injectors and the patients were blinded to which side was treated with what agent. The same dosage and location of injections was used on each side. Patients were treated in the frown area, forehead and crow’s feet.

Patients were assessed and photographed at baseline, and at 3 days, 2 weeks, 3 months and 4 months after treatment.

The photographs were assessed by 3 physicians independently. The physicians were blinded to the treatment, meaning they didn’t know which side was Botox and which was Xeomin. They all used the same rating scale and gave each area a score for the degree of wrinkling still present. The assigned scores were used for the statistical analysis of the results for the 2 agents.

KEY FINDINGS: they found that Botox performed slightly better than Xeomin for dynamic wrinkles. The degree of wrinkle reduction was slightly higher and the duration of the effect was slightly longer with Botox than with Xeomin. These differences were statistically significant.

One reason that may explain why Botox performed better than Xeomin in this study is that the dosages were relatively low. A total of 50 units was used to treat 3 areas (frown, crow’s feet and forehead). The investigators cited scientific reasons for using Xeomin in a 1:1 ratio with Botox but other experts recommend 1.5 units of Xeomin for every unit of Botox. Underdosing can result in an insufficient degree of muscle relaxation and a shortened duration of action.

My recommendation if you are going to a clinic that offers Xeomin or Dysport instead of Botox is to make sure that your injector has lots of experience with these agents. Otherwise you may find that you are not getting the results you’re used to seeing with Botox.