Dysport requires roughly 2.5 to 3 times as many units as Botox to achieve the same effect. So if you’d typically get 20 units of Botox for frown lines, you’d need about 50 to 60 units of Dysport. The two products use completely different unit measurements, which is why the numbers look so different even though the results are comparable.
Why the Units Don’t Match
Botox and Dysport are both made from the same type of botulinum toxin, but they’re manufactured differently and contain different-sized protein complexes. There is no international standard for measuring botulinum toxin potency. Each manufacturer uses its own proprietary testing method to define what “one unit” means, so a unit of Dysport and a unit of Botox are measuring different things entirely. The FDA labels for both products explicitly state that units of one product cannot be compared to or converted into units of another.
That said, practitioners need a practical way to switch patients between products, and decades of clinical research have narrowed down the working ratio. Most published studies place the conversion somewhere between 2:1 and 4:1 (Dysport to Botox), with the strongest evidence clustering around 2.5:1 to 3:1.
The 2.5:1 vs. 3:1 Debate
The manufacturer-recommended dose for frown lines (glabellar lines) is 50 units of Dysport or 20 units of Botox, which works out to a 2.5:1 ratio. This is the ratio the FDA-approved labeling reflects, and it’s what many head-to-head clinical trials use as their starting point.
However, many clinics and practitioners round up to 3:1 for simplicity and because some research supports a slightly higher ratio. A study published in the Journal of the American Academy of Dermatology found that at a 3:1 ratio, Dysport actually produced statistically stronger effects on forehead wrinkles and muscle activity than Botox, suggesting the true equivalence point is somewhere below 3:1. In other words, 3:1 may slightly favor Dysport in terms of potency, while 2.5:1 appears closer to a true match.
For practical purposes, the difference between 2.5:1 and 3:1 is small. Your provider will adjust based on your anatomy, muscle strength, and treatment goals.
Typical Units by Treatment Area
Here’s how the numbers generally break down for common cosmetic areas, using the 2.5:1 ratio from clinical trials:
- Frown lines (glabella): 20 units of Botox vs. 50 units of Dysport
- Forehead lines: 6 to 15 units of Botox vs. 15 to 37 units of Dysport
- Crow’s feet (per side): 10 to 12 units of Botox vs. 25 to 30 units of Dysport
A prospective randomized trial in the Aesthetic Surgery Journal compared the two products side by side on the same patients, injecting Botox on one half of the face and Dysport on the other at a 2.5:1 ratio. The specific doses used were 8 units of Botox vs. 20 units of Dysport for frown lines, 6 vs. 15 for the forehead, and 11 vs. 27 for crow’s feet. Both sides showed equivalent improvement through 150 days, with no statistically significant difference in results at any point.
How Dysport Spreads Differently
Dysport contains smaller protein molecules than Botox, which causes it to diffuse more widely once injected. This makes it well suited for larger, flatter areas like the forehead, where a broader spread can create a smoother, more even result with fewer injection points. Botox stays more localized, which gives providers more precision for smaller, targeted areas.
This difference in spread is one reason the unit conversion isn’t perfectly consistent across every treatment area. Your provider may adjust the ratio slightly depending on where they’re injecting and how much diffusion they want.
Onset and Duration
Research suggests Dysport may kick in slightly faster than Botox. Some patients notice results within two to three days with Dysport, while Botox typically takes closer to four to seven days. One clinical trial also found that Dysport produced significantly less injection pain than Botox.
Duration is roughly comparable. The side-by-side trial found both products still showing measurable improvement at 150 days (about five months), with similar percentages of patients maintaining results at that point: 64% vs. 60% for forehead lines and 43% vs. 45% for frown lines. Some manufacturer-sponsored research suggests Dysport may last slightly longer for forehead wrinkles, but independent studies generally show the two products performing similarly over time.
Cost Comparison
Dysport costs less per unit than Botox, typically $4 to $8 per unit compared to $10 to $25 per unit for Botox. But since you need roughly 2.5 to 3 times as many Dysport units, the total treatment cost usually ends up in the same range. For frown lines, you might pay for 20 units of Botox or 50 to 60 units of Dysport, and the final bill will be similar.
Pricing varies significantly by provider and region, so it’s worth asking for the total treatment cost rather than comparing per-unit prices. Some providers price Dysport slightly lower overall to attract patients willing to try it, but this isn’t universal.
Switching Between Products
If you’re happy with your Botox results and want to try Dysport (or vice versa), your provider will use the conversion ratio as a starting point and may fine-tune from there. The two products are not identical in how they spread, how quickly they work, or exactly how they feel, so the first session with a new product is partly a calibration. Most people find the experience and results very similar once the dosing is dialed in.
Keep in mind that the 2.5:1 ratio was established primarily for cosmetic use on the upper face. For medical uses like excessive sweating, clinical data has pointed to a lower ratio, closer to 2:1. The conversion is not one-size-fits-all, and the right number of units depends on the specific condition being treated.