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A 2026 study of 23 participants found statistically significant improvements versus a vehicle after eight weeks of using a minimalist concentrate with 10% azelaic acid and 0.1% retinal. Azepur99 was the azelaic acid ingredient, but the findings apply to the complete formulation, not that ingredient alone.
A randomized, split-face study published in the International Journal of Cosmetic Science reported improvements in redness, pores, surface irregularities and texture after participants used a concentrate containing 10% azelaic acid and 0.1% retinal for eight weeks. The study included 23 participants who completed it, and compared the finished formulation with its vehicle; the results concern the combined formula, which used Azepur99 as its azelaic acid source, rather than Azepur99 on its own.
The study by Gaudicheau, Ahlström, Gillbro and Åkerström was a prospective, randomized, vehicle-controlled split-face trial. Efficacy assessments used Antera 3D imaging, standardized photographs and participant self-assessments. The report says the active formulation produced statistically significant improvements compared with the vehicle after eight weeks.
Instrumental measurements showed an 18.1% improvement in overall redness, a 12.7% improvement in surface irregularities and a 22.3% improvement in pore parameters. Skin texture improved by 5.6%, while maximum redness intensity fell by 5.2%. These percentages describe outcomes reported for the study’s full formulation and comparison; they do not establish the effect of azelaic acid or retinal separately.
Participants’ self-assessments also favored the active formula: 95% reported calmer-feeling skin, 87% said their overall skin condition improved and 82% reported reduced oiliness. Improvements in pimple size or severity and in the number of pimples were reported by 78% and 74%, respectively. The article describes a six-ingredient concentrate containing squalane, azelaic acid, caprylic/capric triglyceride, hydrogenated vegetable oil, Hordeum vulgare seed flour and retinal.
Results Apply to the Full Formula
The findings offer a clinical evaluation of a finished product combining 10% azelaic acid with 0.1% retinal, rather than evidence about either ingredient in isolation. That distinction matters to consumers and formulators: the measured effects reflect the complete concentrate and the study conditions, so they cannot be used to predict the performance of Azepur99 in other products or of azelaic acid alone.
The trial also provides comparative results against a vehicle, giving more information than consumer feedback alone. Still, it was an eight-week study with 23 completers. The results are a limited evidence base and do not, by themselves, establish how the formula performs over longer periods or across broader populations.
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How Azepur99 Was Used
Azelaic acid is used in skincare products, including products formulated for blemish-prone skin and concerns such as visible redness and uneven tone or texture. The study addressed the finished product’s efficacy and tolerability, evaluating an anhydrous, minimalist concentrate rather than testing an ingredient in isolation.
According to the source report, Azepur99, supplied by Azeco Cosmeceuticals, was the cosmetic-grade azelaic acid used in the formula. The supplier describes it as having at least 99% purity, natural origin and a micronized particle size. Azeco did not take part in the study design, execution, data analysis or publication; its involvement was limited to supplying the ingredient used in the tested formulation.
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Limits of the Eight-Week Trial
The reported results leave several points open. The source material identifies 23 study completers but does not provide enough detail here to assess how representative they were, how large the effects were for individual participants, or whether benefits continued beyond eight weeks. It also does not establish how the formula compares with other treatments or products.
The study evaluated a combination of azelaic acid and retinal, alongside the other ingredients in the concentrate. It therefore cannot show which component contributed to a particular outcome. The provided report does not detail adverse events or give a fuller breakdown of tolerability, so the extent of any irritation or other safety concerns cannot be determined from this material.
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Further Evidence and Publication Details
The study is published as Gaudicheau C, Ahlström M, Gillbro JM and Åkerström U, “Efficacy and safety of a novel anhydrous 0.1% retinal and 10% azelaic acid concentrate for blemish-prone skin: An eight-week randomized prospective split-face, vehicle-controlled study,” in the International Journal of Cosmetic Science (2026), DOI: 10.1111/ics.70131. Readers seeking more detail can consult the full paper for its methods, safety findings and statistical analysis.
Further studies would be needed to assess longer-term use, results in larger or different participant groups, and the contributions of the individual ingredients. The information provided does not announce a follow-up trial or a new study milestone.
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Key Questions
What did the study test?
It tested an anhydrous concentrate with 10% azelaic acid and 0.1% retinal over eight weeks, comparing the finished active formula with its vehicle in a split-face study.
Did the study prove Azepur99 alone improves skin?
No. Azepur99 was the azelaic acid source used, but the outcomes were measured for the complete formulation. The study does not isolate its effects.
How many people completed the study?
Twenty-three participants completed the eight-week study, according to the source report.
What improvements did participants report?
In self-assessments, 95% reported calmer-feeling skin, 87% an improvement in overall skin condition, and 82% reduced oiliness. These are participant-reported results for the studied formula.
Who supplied the azelaic acid?
Azeco Cosmeceuticals supplied Azepur99 for the formulation. The source says the company did not participate in the study design, execution, analysis or publication.
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