A fast-acting toxin before the usual one in aesthetic treatments: no new safety concerns

If you have ever wondered about aesthetic treatments for frown lines, here is a calm, reassuring bit of news. Researchers tried a fast-acting toxin first, then the usual wrinkle toxin 30 days later, and found no new safety concerns.

Nothing changes for you today. But it shows where the field is heading: giving people a quicker way to see a result before moving to a longer-lasting product.

How the study worked

This was a phase 1 study, the early stage of testing, with 90 participants who had moderate to severe frown lines. On day 1, each person got either a placebo or a fast-acting type E toxin called trenibotulinumtoxinE (trenibotE), at 700 U. On day 30, 85 of them got onabotulinumtoxinA (onabotA), a type A toxin, at 20 U. Everyone was followed through day 150. Both the investigators and the participants rated the lines on a standard wrinkle scale while frowning as hard as possible. The study was published Oct. 27, 2026, in the Aesthetic Surgery Journal. It was built mainly to check safety, so it can’t tell us how long the type E effect lasts or how satisfied people felt.

What they found

The main goal was to see how many people had “none” or “mild” frown lines at day 60. That rate was similar whether people had first received the placebo or trenibotE.

The fast-acting toxin did its job early. The share of people with none or mild lines peaked around day 7 with trenibotE. With onabotA, it peaked at day 60, which is 30 days after that shot. The two peaks were similar.

On safety, the news was good:

• Most side effects were mild, not serious and not related to the treatment.
• No participants developed antibodies, either binding or neutralizing, against trenibotE or onabotA.
• Taken together, the study identified no new safety concerns.

In plain words, getting the type E toxin first did not seem to get in the way of the type A toxin that followed. Overall, the sequence generally improved frown lines, as judged by both patients and clinicians.

What are frown lines, and why two toxins?

The doctors call them glabellar lines. They are the vertical lines between your eyebrows that deepen when you frown. Botulinum toxins relax the small muscles that pull the skin together there.

Type A toxins are widely used for this. Some people hesitate to try them because they are unsure how the result will turn out. Type E is a different kind of toxin with its own profile, and it acts fast. The idea behind this study is simple: a quick preview first, then the familiar option.

The antibody check matters too. Researchers want to be sure that one product does not make the next one work less well. In this study, that did not happen.

What you can do today

If you are curious about frown line treatments, take two minutes to write down three questions before you book anything: Is this product FDA-approved? Will a licensed clinician do the injection? What are the most common side effects? Bring that list to your consultation and see how clearly you get answers.