Botulinum preparations: does the type change effectiveness? When comparing, check the "dose" and "duration"

When botulinum preparations are compared at equivalent doses adjusted for type, there is no significant difference in wrinkle-suppressing power[1]. However, because the strength of "1 unit" differs by preparation, the actual content is not the same even at the same numerical dose[2]. When choosing, rather than relying on the name, it is more practical to confirm how many units of that preparation will be injected and how long the effect will last.

How much does effectiveness differ depending on the preparation?

In a study comparing three types using the same method for frown lines, all were effective, and none was notably superior[1]. In research on injections into the masseter muscle (chewing muscle) in people from East Asia and Southeast Asia, when compared at the same dose, the effects were reported to be similar[3].

A preparation called incobotulinumtoxinA has also been reported to be effective for at least 12 weeks, comparable to conventional preparations[4].

Where are differences most likely to appear?

Differences most often appear in how quickly effects begin and in the strength per unit. In the same research, differences in muscle inhibition were observed between preparations at 4 days and 14 days after injection[1].

The strength of 1 unit differs by preparation, and there are conversion guidelines[2]. For example, abobotulinumtoxinA is considered equivalent at approximately 2–6 times the unit count of other preparations[2]. Spread patterns are also said to have characteristics specific to each preparation[5].

Therefore, results obtained from one preparation cannot be directly applied to a different preparation[6]. Ask "how many units were injected" together with the preparation name.

How long does the effect last?

Effects typically begin 3–10 days after injection and last approximately 3–6 months[2]. With incobotulinumtoxinA, the effect may last 5 months or longer[7].

Duration depends not only on the preparation but also on the dose. It has been reported that injecting less than the recommended dose tends to result in weaker effect and shorter duration[8]. No evidence has been found that reducing the dose decreases side effects[8].

Can it become less effective with repeated treatments?

Rarely, repeated treatments may result in reduced effectiveness[9]. In a survey of 919 people receiving treatment in the United Kingdom, 2.9% reported reduced effectiveness[9].

This is based on self-reporting by patients and does not confirm the underlying cause. One suspected cause is the body developing antibodies against the preparation. However, the likelihood of this occurring is low, and no clear difference has been demonstrated among the three main preparations[10].

How do I choose the right preparation for me?

When choosing, it helps to check the following three points in order: First, which preparation and how many units will be injected into which area. Second, the timeline for effect onset and duration. Third, how effective it was the previous time.

If the previous effect was weaker or lasted shorter than before, this experience can guide reconsideration of the preparation and dose. If you know the name and date of previous injections, keep a note and bring it with you.

Based on this article alone, you cannot decide which preparation and dose is right for you. During your consultation, tell your doctor which area you want treated and the strength of the muscle, explain how it worked previously, and confirm the reasons for the recommended preparation and unit count.