Efficacy and Safety of a Novel 0.1% Retinal and 10% Azelaic Acid Anhydrous Concentrate for Blemish-Prone Skin: An Eight-Week Randomized, Prospective, Vehicle-Controlled Split-Face Study

Chloé Gaudicheau, Maria Ahlström, Johanna Maria Gillbro, Ulf Åkerström

Randomised Clinical Study | Placebo Split-Face | Skinome Research AB

Blemish-prone skin is affected by follicular hyperkeratinization, excessive sebum production, microbial dysbiosis, and inflammation, often combined with post-inflammatory erythema and hyperpigmentation. Retinal and azelaic acid are well-established topical active ingredients with complementary mechanisms of action, but to date, no clinical study has evaluated their combination in a single formulation.

To evaluate the efficacy and tolerability of a minimalist, anhydrous concentrate combining retinal (0.1%) and azelaic acid (10%) in improving both objectively measured and self-perceived characteristics of blemish-prone skin over an eight-week period.

In a prospective, randomized, vehicle-controlled, split-face study, participants applied the active concentrate to one side of the face and a vehicle concentrate to the opposite side. The concentrates were mixed with a moisturizer immediately before application.

Evaluations were conducted at the start of the study and after eight weeks using standardized photography, Antera 3D image analysis, and participant questionnaires. Statistical comparisons were performed both within each participant and between the treatment groups.

Twenty-three participants completed the study (16–49 years; mean age 28 years; Fitzpatrick skin types I–IV).

After eight weeks, the active formulation demonstrated statistically significant improvements compared to both baseline values and the vehicle.

Skin texture improved by 10.9% from baseline (p < 0.0001) and by 5.6% from vehicle (p = 0.0016).

The skin volume parameter, which reflects irregularities and depressions in the skin surface, decreased by 24.8% compared to baseline (p < 0.0001) and by 12.7% compared to the vehicle (p = 0.0053).

Total skin redness decreased by 13.2% compared to baseline (p = 0.0009) and by 18.1% compared to vehicle (p = 0.011). The maximum intensity of redness decreased simultaneously by 8.8% compared to baseline (p < 0.0001) and by 5.2% compared to vehicle (p = 0.029).

The pore parameter improved by 22.3% compared to vehicle (p = 0.015) and by 15.9% compared to baseline (p = 0.051).

Participants' self-assessments showed improvements in general skin condition (87%), pimple size and severity (78%), number of pimples (74%), a calmer skin sensation (95%), and reduced oiliness (82%).

A total of 65% of participants reported visible improvements within four weeks. Side effects were few, mild, and transient.

An anhydrous concentrate comprising six ingredients and containing 0.1% retinal and 10% azelaic acid showed significant improvements in skin texture, unevenness, redness, and the appearance of pores in acne-prone skin after eight weeks, with good tolerability.

The formulation offers a stability-optimized way to combine two evidence-based active ingredients in a minimalist formulation.