How Many Units of Dysport vs. Botox: Key Differences

Dysport and Botox both use the same active molecule, but their units are not equivalent. The most commonly referenced conversion ratio is roughly 2.5:1 to 3:1, meaning you need about two-and-a-half to three Dysport units for every one unit of Botox. That sounds straightforward, but the real-world picture is messier than a single number suggests, and which ratio a provider uses depends on the treatment area, the clinical goal, and how the individual patient responds.

Why the Units Are Not Interchangeable

Both Dysport (abobotulinumtoxinA) and Botox (onabotulinumtoxinA) work through the same 150 kDa botulinum neurotoxin type A molecule, but each product is manufactured differently and tested with its own proprietary potency assay.¹ Think of it like comparing miles and kilometers: the underlying reality is the same distance, but the measuring systems produce different numbers. One “unit” of Botox is defined by one lab test, and one “unit” of Dysport is defined by a different lab test. Neither company’s unit maps directly onto the other’s, which is why regulators and manufacturers insist the products are non-interchangeable on a unit-for-unit basis.

The differences go beyond labeling. The two products contain different amounts of complexing proteins, use different excipients, and are stored and reconstituted under different protocols. Dysport’s biological availability can actually shift depending on dilution volume and whether albumin is added during reconstitution.² These formulation details mean that even if you nail the “right” unit number, factors like how the vial was prepared can influence the clinical result.

The Conversion Ratio Debate

For years, many practitioners defaulted to a 3:1 ratio, using three Dysport units for every one Botox unit. A broad review of clinical and preclinical data across conditions like spasticity, cervical dystonia, and blepharospasm concluded that a 3:1 ratio, or even something lower, is appropriate, and that going higher risks overdosing Dysport.³ A separate literature review reached the same conclusion, recommending that physicians start with a lower conversion factor and adjust upward based on how the individual patient responds.⁴

But a 2.5:1 ratio has strong support too. A double-blind trial in cervical dystonia patients found that Dysport and Botox were comparable in safety and efficacy when dosed at 2.5:1, with no statistically significant difference in symptom improvement at four weeks.⁵ Meanwhile, a crossover trial testing both 3:1 and 1.7:1 ratios found that the 3:1 ratio actually resulted in suboptimal Botox efficacy compared to Dysport at twelve weeks, hinting the true equivalence might sit below 3:1.⁶

The honest takeaway is that there is no single universally correct ratio. Most evidence clusters around 2.5:1 to 3:1, but the optimal number varies by indication, by muscle group, and by patient. Providers who treat both products regularly tend to develop a feel for where in that range a given patient falls, adjusting across sessions rather than locking in one number forever.

What This Looks Like in Common Cosmetic Areas

In practice, the conversion ratio translates into specific unit counts that patients hear about during consultations. The numbers below reflect typical ranges, not rigid prescriptions, because every face is different.

For glabellar lines (the “11s” between the brows), a standard Botox dose is often around 20 units, which translates to roughly 50 to 60 Dysport units. A randomized split-face trial comparing the two products at standard doses found no statistically significant differences in wrinkle improvement across glabellar, forehead, and crow’s feet areas over 150 days.⁷ Both products yielded measurable improvements that lasted beyond what manufacturer guidelines suggest.

For forehead lines, Botox doses commonly range from 10 to 30 units depending on the patient’s muscle strength, with Dysport equivalents running roughly 25 to 75 units. The forehead is where overzealous dosing can flatten natural expression, so providers often err on the conservative side and add more at a follow-up if needed.

Crow’s feet typically call for about 8 to 16 Botox units per side, or roughly 20 to 40 Dysport units per side. Interestingly, one prospective study found that Dysport showed a higher percentage of patients with earlier onset of improvement in the crow’s feet region and appeared to last longer for a greater proportion of patients at the four-month mark compared to Botox.⁸

For masseter reduction, which slims the jawline and can help with teeth grinding, the doses climb considerably. A clinical trial used 75 Dysport units per masseter muscle (150 total), noting that this was comparable to roughly 30 units of Botox per side.⁹ These are large muscles, and treating them requires substantially more product than the fine muscles of the upper face.

Onset Speed and How Long Results Last

Patients often ask whether one product “kicks in” faster or lasts longer. The evidence is somewhat mixed, and it depends on what you’re treating. In the crow’s feet and glabellar regions, the triple-blind study mentioned earlier reported that Dysport tended to show improvement sooner, and evaluator assessments found it lasting longer at the four-month mark: about 83% of patients still showed benefit with Dysport versus 48% with Botox in the glabellar area, and 65% versus 47% in the crow’s feet area.⁸

However, a review of facial aesthetic applications estimated Dysport’s mean retreatment interval at about 3.9 months, and a single comparative study found that the proportion of patients relapsing at week 16 was lower in the Botox group (about 23%) than in the Dysport group (about 40%).¹⁰ These seemingly contradictory findings illustrate that study design, dose ratios, and how “relapse” is defined can swing the comparison in different directions. The split-face trial comparing the two products on forehead wrinkles found both were still effective at 150 days, well past the three-to-four-month window most patients expect.⁷

The practical lesson: neither product has a clear, consistent edge on duration across all treatment areas. If you’re happy with one product’s longevity, that’s a reasonable factor in sticking with it. If your results seem to fade faster than expected, adjusting dose or switching products is worth discussing with your provider.

Diffusion and Spread

One claim you’ll hear repeated in waiting rooms and online forums is that Dysport “spreads more.” This reputation has some basis in early observations, but modern evidence suggests the picture is more about dose than about some inherent spreading property. Different formulations of botulinum toxin do show differences in distribution patterns.¹¹ However, a study of 59 women with forehead wrinkles found that at a 2:1 Dysport-to-Botox dose ratio, the two products produced statistically equivalent fields of effect. Only at a higher 2.5:1 ratio did Dysport create a measurably larger area of spread.¹²

This matters practically. Greater spread can be an advantage when you want to cover a large area like the forehead with fewer injection points. It can be a disadvantage when precision is critical, such as around the delicate muscles of the eyelid. Experienced injectors account for this by adjusting their technique, injection volume, and placement based on which product they’re using. Injection patterns established for one formulation are not automatically transferable to another.¹¹

Treating Hyperhidrosis

Both products are used off-label (and in some countries on-label) for excessive sweating. A same-patient comparison that treated one armpit with 100 units of Botox and the other with 300 units of Dysport (a 1:3 ratio) found that both eliminated sweating equally at the two-week mark. But the timeline differed: Botox showed a dramatic reduction after just one week, while Dysport took two weeks to reach the same point. More strikingly, the Botox side stayed dry for about nine months compared to six months for Dysport.¹³

For palmar hyperhidrosis, a study of 36 patients comparing Dysport at various concentrations to Botox found that Dysport at a 2:1 concentration ratio was actually more potent than Botox, and that the truly equivalent concentration fell somewhere between a 1:1 and 1.5:1 ratio.¹⁴ This lower-than-expected ratio in the hands underscores why a single conversion number can’t be blindly applied across every body site.

Safety and Side Effects

At appropriately equivalent doses, the two products share a similar safety profile. In a long-term study of patients treated for hemifacial spasm, side effects occurred in about 17% of all treatments, with no statistically significant difference between Botox (about 17% of treatments) and Dysport (about 20%). The most common issues were eyelid drooping and tearing. One difference that did reach statistical significance: drooping eyelid and incomplete eyelid closure were more common with Dysport treatments.¹⁵

A large analysis of adverse event reports submitted to the FDA found that both Botox and Dysport had elevated reporting rates for eyelid and eyebrow drooping, facial weakness, and botulism-like symptoms. Dysport specifically showed elevated reporting for muscular weakness and difficulty swallowing, while these signals were not significant for Botox in that database.¹⁶ These reporting-rate differences should be interpreted carefully. Botox has vastly more users worldwide, which affects both the raw counts and the types of events that get reported. The overall side-effect profile for both products in cosmetic use remains favorable when administered by trained providers at appropriate doses.

Immune Response and Losing Effectiveness Over Time

A concern for long-term users is whether the body will develop antibodies that neutralize the toxin, causing treatments to gradually stop working. Both products can trigger antibody formation, and the risk depends partly on how much total neurotoxin protein is presented to the immune system over time. Interestingly, Dysport has a higher “specific biological activity,” meaning each nanogram of neurotoxin in the preparation produces more units of clinical effect. Botox comes in at about 60 mouse units per nanogram of neurotoxin, while Dysport clocks about 100 mouse units per nanogram.¹⁷ In theory, this means Dysport delivers less raw protein for the same clinical effect, which could translate to a slightly lower immunogenic burden. In practice, however, no obvious differences in antibody formation between the two type-A products have been detected.

If you feel your results are declining after years of treatment, the first suspects are usually injection technique and dose adequacy rather than true antibody-mediated resistance. True immunoresistance is uncommon in cosmetic patients, who use lower doses and longer intervals than patients treated for neurological conditions.

Switching Between Products

Some patients switch products because of cost, availability, or dissatisfaction with results. The conversion ratios discussed earlier serve as a starting point, but switching is not always a simple math exercise. In one study of patients with neurogenic bladder problems who had stopped responding to Botox, more than half regained clinical benefit after switching to Dysport.¹⁸ This suggests the two products are not perfectly redundant in how they affect tissue, and a switch can sometimes restore effectiveness.

For cosmetic patients, switching is generally straightforward. Your provider will translate the dose using the 2.5:1 to 3:1 range, often starting on the conservative end and adjusting at a follow-up. The main thing to be aware of is that onset timing, spread, and duration may feel slightly different, so your first session with a new product is partly a calibration visit.

The Cost Factor

Dysport typically costs less per unit than Botox, but since you need more units, the total price for a treatment session often comes out similar. In some markets and practices, the math does favor Dysport, especially for larger treatment areas where the per-unit savings compound. The split-face trial comparing both products for forehead and glabellar wrinkles found comparable efficacy but noted that Dysport offered significant cost savings at the pricing available at the time of the study.⁷

Pricing varies widely between clinics and regions, and many practices run promotions or loyalty programs that can tip the balance. When comparing quotes, make sure you’re comparing total treatment cost rather than per-unit cost, since the unit counts are so different. A quote of “50 units of Dysport for your forehead” and “20 units of Botox for your forehead” may represent roughly the same treatment, just described in different currencies.

Reconstitution Choices That Affect Your Results

Something most patients never think about is how the product was mixed before it reached the syringe. Both Dysport and Botox come as freeze-dried powders that must be reconstituted with saline before injection. The amount of saline used changes the concentration: more saline means a more dilute solution, which can increase the volume injected per point and potentially affect how far the product spreads. Research has shown that Dysport’s biological activity can be enhanced by lowering the concentration (using more saline) and by adding albumin as a stabilizer.²

In cosmetic practice, most providers follow fairly standard dilution protocols, but there’s room for variation. A provider who dilutes Dysport more aggressively might get a broader field of effect from fewer injection points, which could be ideal for the forehead but problematic near the eyes. If you switch clinics and notice your results feel different even though the “dose” on paper is the same, ask about the dilution. It is one of those behind-the-scenes variables that can meaningfully change the outcome.