Botulinum Toxin 2014: Tips, Thoughts, Science, & Different Formulations


Joel L. Cohen, MD

In this presentation, Dr Joel Cohen, a leader in aesthetic dermatology, and the Director of AboutSkin Dermatology and DermSurgery in Colorado, provides us with an update on the use of botulinum toxin. Dr Cohen begins the session by reminding us, as Dermatologists, that every day we have an opportunity to blend our modalities, i.e., medical, surgical, and aesthetic in order to provide our patients with the best possible outcomes.

Currently, there are three FDA-approved botulinum toxins type A; these are Botox (Allergan), Dysport (Medicis/Galderma), and Xeomin (Merz). All three products are approved to treat glabellar lines; however, Botox was also recently approved for the treatment of Crow’s feet.

Cox and Finn a decade ago, found that botulinum toxin type A injections have been beneficial for patients who feel that their faces are not communicating their emotions properly, want to delay the outward appearance of aging, and/or patients simply want to look their best. Data also suggest that botulinum toxin type A injections can also affect self-esteem. A 2010 health-outcomes survey (randomized data), conducted by Dayan and colleagues, found that the injection of botulinum toxin type A injections demonstrated improvements in quality of life (QOL) and self-esteem and injection-naïve patients demonstrated greater improvements in QOL and self-esteem versus those who had received previous injections.

All three of the FDA-approved products contain a core neurotoxin protein (150 kD BoNT/A), this is where the mechanism of action lies.  Botox and Dysport are wrapped in protein, which is part of the neurotoxin complex. Xeomin; however, lacks these accessory proteins. All three products have demonstrated efficacy and have established good safety profiles, but remember that it is difficult to make direct comparisons among the approved botulinum toxins. Keep in mind that the products are different, the dosing can be different, the studies were all designed differently and there are differences among the various study endpoints.

Conversation Ratios

Keep in mind that the three neuromodulators approved for aesthetic use are separate products; therefore, there is no TRUE or EXACT “conversion ratio”. As dermatologists, we must learn how to use each product differently in clinical practice. The injection techniques are similar; however, there are no direct specific or perfect conversion ratios.  Regulatory agencies around the world, including the United States, have recognized that these are different products, and there is no interchangeability among botulinum toxin neuromodulators.


Sattler, et al published a non-inferiority trial comparing Xeomin to Botox in the treatment of glabellar frown lines. The independent rater and patient assessment between both products were very similar at weeks four and 12.  Because this was a non-inferiority study with two time-points, you can miss the “duration of efficacy” and the “waning effect.” The authors concluded that Xeomin is equally as effective as Botox and both preparations were well tolerated.

Other Considerations

When we look at the FDA studies for the available neuromodulators, they dose the medial corrugator exactly the same as the lateral corrugator and for the convenience of an FDA study. For Botox and Xeomin, it was four units in five injection points and for Dysport it was ten units in five injection points. The reality of our practice is that patients typically have a much more prominent medial corrugator than a lateral corrugator, and when you inject the lateral corrugator with a large dose you risk unwanted spread to the frontalis, which can knock-out the lateral frontalis function of keeping the brow up. So consider lower doses in the lateral corrugator when appropriate, and consider orienting the needle tip more medially to avoid lateral spread to the frontalis.

Combination Delivery

Combining fillers and neuromodulators in the same syringe is not something I would recommend and is considered controversial. It is ok to consider combination therapy, as there is good data on this, but not in the same syringe. In 2013, Drs Cohen and Mariwalla wrote a letter to the editor of Journal of Drugs in Dermatology referencing an article whereby these products were mixed in the same syringe, cautioning practitioners about the potential pitfalls of this sort of approach.  Keep in mind that combination same-syringe delivery (e.g. botulinum toxin-A and hyaluronic acid filler ”mixed together”) can be imprecise on many levels, from not uniformly mixed to potential unintended spread of one of the agents. I personally think it would take more time to mix the neuromodulator in the filler syringe, then to simply draw up and inject the Botox on its own—and on its own seems much more precise.

Another important consideration is that of combination neuromodulators and chemical peels on the same day. Swelling can potentially carry a neuromodulator, even a centimeter or two. Use caution on the same day and in same region as procedures that may cause significant swelling with regards to migration, such as non-ablative fractional, ablative fractional, higher concentration chemical peels, and even tightening devices.


Remember that dosing, dilution, and reconstitution are different concepts. Dr Cohen reconstitutes his neuromodulators differently by region, using 1cc dilution per 100 units (Botox/Xeomin) in most areas (glabellar, lateral canthus, DAO, and mentalis); however, he uses 5cc for the perioral lines, forehead, platysmal bands, and hyperhidrosis.

When looking specifically at dosing, aesthetic physicians have historically used high-dosages in the forehead, which often caused them to look completely “flat”.  “Many patients prefer simply softening the musculature in the forehead without totally knocking it out — achieving a relaxed and natural look. Over the years, Dr Cohen and colleagues have found that they can basically cut the forehead dose in half. This helps in achieving a natural look, softens the musculature and maintains brow shape and positioning–many patients prefer. There are published consensus statements and recommendations on how much product to use and how best to use it for each of the products available. As dermatologists, we also need to consider the anatomic differences between men and women and how we approach the use of neuromodulators in the forehead.


Remember that all three products have demonstrated positive efficacy and safety profiles. As clinicians, it is important to understand how to use each product, their differences and most importantly, how to individualize treatment and set realistic expectations for our patients. Utilizing the Merz scales or other scales can help with achieving aesthetic treatment goals, by explaining to patients their point on a scale now versus where you are striving to get them to after treatment.

It is critical to understand the changes and differences in the FDA requirements in the studies for neuromodulators. When Botox was approved, studies were designed differently—and improvement was scored differently with follow-up evaluations looking at persistence of some degree of improvement (but not 2-grade improvement necessarily). With Xeomin, a two-grade improvement was required, which was a much higher standard. This is an important concept to keep in mind when looking at responder rates over various studies. With the recent approval of Botox for Crow’s feet, Allergan similarly was held to the 2-grade improvement scale as well.