Lip filler: what lasts at 48 weeks?

A fuller appearance soon after lip filler does not answer how much of that change will remain months later. It also does not establish that one product is better than another. A randomized trial of Belotero Intense with lidocaine illustrates why those are separate questions.

The paper published on 15 October 2026 in Aesthetic Surgery Journal compares this hyaluronic acid filler with Restylane Silk with lidocaine. The underlying trial was completed in September 2024; its ClinicalTrials.gov results were first posted on 18 August 2026. This is an analysis of that evidence, not a newly completed trial.

## An early result, with a defined denominator

The registry records 220 adults allocated at random: 165 to Belotero and 55 to Restylane. Eligibility was limited to ages 21–65, and 212 participants were women. A blinded assessor rated lip fullness; an optional touch-up was allowed at week four.

At week eight, 144 of the 158 Belotero recipients included in the primary per-protocol analysis met the response threshold: at least a one-grade improvement on the lip-fullness scale. That is 91.1%, not 91.1% of everyone randomized. The corresponding Restylane analysis included 52 people and reported a 90.4% response rate.

The comparison of average improvement met the study’s predefined noninferiority margin. It supports a narrow conclusion: Belotero was not worse by the amount the trial had defined as unacceptable. It does not establish superiority, identical results or that either option will suit every person.

## The 48-week figure answers a narrower question

Among an analyzed subgroup of 137 early responders, 70, or 51.1%, retained improvement through week 48. This was a post hoc analysis, devised after the original analysis plan, and cannot be read as the probability of a lasting result for all 165 Belotero recipients. Nor does it establish that Belotero lasts longer than the comparator. Optional retreatment at week 48 was offered only to Belotero recipients.

## No related serious event does not mean no reaction

The abstract reports no severe or serious treatment-related adverse events. The registry nevertheless records delayed treatment-related events in 4/165 Belotero and 3/55 Restylane recipients; delayed means onset more than 21 days after the last treatment. This prespecified safety outcome covered up to 48 weeks in both groups. It also lists injection-site lumps in 27/165 and 6/55, respectively. These findings should accompany the early fullness result.

The separate general adverse-event tables, including events regardless of their relation to treatment, covered up to 60 weeks for Belotero and 48 for Restylane. These unequal windows make simple comparisons of the rates in those tables misleading; they do not apply to the shared 48-week delayed-event outcome. Two serious events recorded in the Belotero group—gallbladder inflammation and a femur fracture—were not counted as treatment-related. A study of this size cannot exclude rare harms.

Merz North America funded and sponsored the trial. The registry describes an agreement requiring sponsor involvement in publication. The full paper and complete individual author disclosures were unavailable for this analysis; its basis is the abstract, publisher metadata and public trial results. The useful finding is therefore a measured early effect with qualified durability data, rather than a guarantee about longevity or safety.