CLINICAL EFFICACY EVIDENCE REVIEW
Clinical Evidence Review of Retinal (Retinaldehyde) for Skin Benefits
NanoActive® RAL nano-encapsulated retinal · Focus on pore improvement and anti-wrinkle efficacy · Peer-reviewed literature + proprietary Intertek human efficacy data
KEY NUMBERS
More than 30 years of clinical evidence focused on pores and wrinkles
| Evidence base | Randomized trials | Wrinkle improvement | Pore improvement |
|---|---|---|---|
| 19 human clinical studies1994–2026 | 6+ RCTs | −43.2%wrinkle-count improvement in 28 days with liposomal RAL | +20%pore improvement after 8 weeks with a 0.1% retinal serum |
Evidence focus
Required focus: pore appearance · wrinkle reductionAdditional benefits: skin texture · elasticity/firmness · pigment evenness · barrier/TEWL · redness · tolerability and safety
PuriPharm Co., Ltd. · Compiled from RCTs and international peer-reviewed journals, prioritizing US/global evidence · September 2026
EXECUTIVE SUMMARY
More than three decades of peer-reviewed evidence support the skin benefits of retinal
Retinal (retinaldehyde) is the immediate metabolic precursor of retinoic acid. More than 30 years of peer-reviewed human evidence span international journals including J Am Acad Dermatol, Dermatology, J Cosmet Dermatol, J Drugs Dermatol (US), and Dermatol Ther.
- Wrinkles: ≥10 human studies of 0.05–0.1% RAL, ranging from a 7.6% reduction in crow’s-feet depth at 8 weeks (RCT; comparable with glycolic-acid peels) to 27–34% reductions in wrinkle scores at 90 days in the largest cohort (n=1,462).
- Pores: A 2024 US JDD study reported a 20% improvement in pore appearance after 8 weeks with a 0.1% retinal serum (P<0.0001). A nanovesicular RAL study showed a 23.6% reduction in sebum after 4 weeks and significant reductions in open and closed comedones—the mechanistic basis for improved pore appearance.
- Liposomal / nano-encapsulated delivery: Human studies across four delivery technologies—multilamellar vesicles, liposomes, niosomes, and exosomes—reported efficacy comparable or superior to non-encapsulated comparators with good tolerability. In a proprietary 4-week Intertek human test of NanoActive® RAL serum (n=30), crow’s-feet count decreased 31.0%, forehead-wrinkle count decreased 27.7%, and skin-tone ITA° increased 12.0% (all P<0.001), with no adverse events.
Concentration window
All pivotal human studies were conducted at 0.05–0.1%: Creidi 1998 (0.05%); Kwon 2018 (0.05% vs 0.1%); Rouvrais 2018 / JDD 2024 / liposomal 3RC (0.1%); and encapsulated-delivery trials (0.05% and 0.1%).
A 24-week split-face study in 2026 found significant wrinkle improvement with 0.1% in facial areas where 0.05% did not reach significance. In Kwon 2018, only the 0.1% group showed a significant decline in melanin index.
Formulation recommendation: 0.05% for sensitive-skin or daily-use positioning; 0.1% to maximize wrinkle and tone-evening benefits. NanoActive® RAL nano-encapsulated retinal covers this concentration window.
Sources: Creidi 1998 (PMID 9843009); Cordero 2011 (PMID 21649816); Rouvrais 2018 (PMID 30027612); JDD 2024 (PMID 39496127); Kim 2021 (PMID 34587353); Brown 2023 (Springer 10.1007/s13555-023-01004-z)
INGREDIENT POSITIONING
Where retinal sits in the retinoid metabolic pathway
| Retinyl esters | Retinol | Retinaldehyde | Retinoic acid |
|---|---|---|---|
| Retinyl esters | Retinoltwo oxidation steps | Retinaldehydeone oxidation step → active acid | Retinoic acidreceptor-active |
Retinal is only one enzymatic oxidation step from the receptor-active form, retinoic acid, whereas retinol requires two. Retinal therefore combines high biological activity with substantially better tolerability than retinoic acid—a position confirmed in head-to-head clinical studies and authoritative reviews.
Keratinocytes convert retinal to retinoic acid only at specific stages of differentiation, creating a more controlled, self-limiting supply of active acid. This is the biological basis of its lower irritation potential. Retinal also has direct activity against Cutibacterium acnes, attributable to its aldehyde group—an effect not shared by retinol or retinoic acid.
Sources: Saurat 1994 (PMID 7798613); Fluhr 1999 (PMID 10473963); Milosheska & Roškar 2022 (Adv Ther); Pechère 2002 (Dermatology)
EVIDENCE LANDSCAPE
1994–2026: an evidence base led by European, US, and international studies
Figure 1. Human clinical evidence landscape. Bubble size represents sample size on a logarithmic scale; color indicates study region. Two South Korean RCTs provide rare controlled evidence for encapsulated vesicular delivery.
Source: 19 human studies (1994–2026) summarized in Table 1 of the report
ANTI-WRINKLE · FOUNDATIONAL RCT
Creidi 1998: the foundational randomized trial of retinal for wrinkles
- Design: randomized, double-blind, vehicle-controlled, full-face study; n=125 participants with facial photodamage; 44 weeks.
- Groups: 0.05% retinaldehyde cream vs 0.05% retinoic-acid cream vs vehicle. Silicone replicas of crow’s feet were assessed by optical profilometry.
- Results: At week 18, retinaldehyde and retinoic acid significantly reduced wrinkle and roughness features; the vehicle produced no statistically significant change. Benefits were maintained through week 44.
- Tolerability: Retinaldehyde was well tolerated throughout; retinoic acid caused more local irritation and reduced adherence.
Why this study is foundational
It established the core positioning of retinaldehyde as providing efficacy comparable with retinoic acid but substantially better tolerability. Nearly all subsequent cosmetic-retinoid reviews cite this study, and its 18-week onset window became a benchmark for later study durations, including liposomal RAL programs. Objective endpoints—optical profilometry and silicone replicas—provide quantifiable, reproducible claim support.
Source: Creidi et al. 1998, J Am Acad Dermatol (PMID 9843009)
ANTI-WRINKLE · LARGE-SAMPLE AND LONG-TERM EVIDENCE
Large cohorts and long-duration studies confirm wrinkle and structural improvements
| Study | Design / sample | Duration | Key anti-wrinkle results |
|---|---|---|---|
| Cordero 2011J Cosmet Dermatol · international multicenter | Open-label, n=1,462 | 90 days | Crow’s feet −27%; perioral −34%; nasolabial folds −20%; forehead −19% (all P<0.001; profilometry confirmed); elasticity +32–33% |
| Deda 2026Poland · double-blind split-face | n=56; age 30–58 | 24 weeks | 0.1% RAL significantly improved wrinkle parameters (0.05% did not reach significance); dermal density by 50-MHz ultrasound improved comprehensively, suggesting neocollagenesis; elasticity R2 +11.6–12.8% |
| Rouvrais 2018France · RCT vs glycolic-acid peels | n=55 | 8 weeks | Crow’s-feet depth −7.61% (P=.0007), comparable with three professional peels (20%/50%/70%); texture improvement significantly favored RAL (between-group P=.0252); 12-fold fewer adverse signs |
Cumulative long-term benefit
Deda 2026 is currently the longest split-face controlled retinal study. It provides instrument-based evidence of cumulative benefit, with dermal density continuing to rise between weeks 12 and 24.
Sources: Cordero 2011 (PMID 21649816); Deda 2026 (PMC12928007); Rouvrais 2018 (PMID 30027612)
ANTI-WRINKLE · ENCAPSULATED RETINAL
Human anti-wrinkle evidence for encapsulated delivery
−43.2%
28-day improvement in wrinkle count with liposomal RAL 0.1% + retinoid (P<0.001)
Brown 2023 · Dermatol Ther (Spain/Europe)Among 32 participants, including those with sensitive skin, crow’s-feet wrinkle count decreased in 100%; elasticity improved 13.9%, firmness 5.6%, and skin-tone evenness 7.0%, without a retinization period.
Kim 2021 · split-face RCT (South Korea; identified)Multilamellar-vesicle retinal (MLV-RAL) 0.05%/0.1% creams were compared with retinol at matched concentrations. After 8 weeks, wrinkle depth (Antera 3D), hydration, elasticity, and facial contour improved significantly; the MLV-RAL side outperformed the retinol side on every objective measure except dermal density. Neither side had adverse events.
Gold 2026 · J Cosmet Dermatol (US)Twenty women (Fitzpatrick I–VI) used exosome-encapsulated retinal for 12 weeks. Wrinkles/fine lines, erythema, tone, and texture improved significantly from week 2; 100% showed global facial aesthetic improvement at weeks 8 and 12, with no product-related adverse events.
Truchuelo-Díez 2026 · double-blind RCT (Spain)A combination of RAL 0.05% + retinol 0.3% significantly reduced wrinkle depth by day 28 and wrinkle amplitude at study end. Retinol 0.5% alone showed only a trend, indicating that low-dose retinal enabled efficacy approaching that of nearly twice the retinol concentration.
Sources: Brown 2023 (Springer 10.1007/s13555-023-01004-z); Kim 2021 (PMID 33569865); Gold 2026 (PMID 41735774); Truchuelo-Díez 2026 (MDPI 2079-9284/13/3/133)
PORE IMPROVEMENT · DIRECT ENDPOINT
A US clinical study directly documented improvement in pore appearance
+20%
Improvement in pore appearance after 8 weeks with a 0.1% retinal serum (P<0.0001)
JDD 2024 · J Drugs Dermatol (US)Thirty-two women—47% with skin of color and 57% with sensitive skin—applied the product to the face, neck, and chest three nights per week. Concurrent improvements were 12% for facial fine lines, 19% for chest fine lines, 19% for hyperpigmentation, and 5% for texture. Patch testing showed no sensitization or irritation.
Claim-use caveat
This was a single-arm, multicomponent finished-product study without a vehicle control. It therefore supports the statement that “a 0.1% retinal formulation improved pore appearance by 20% in 8 weeks,” not independent attribution to a single ingredient. In technical dossiers, it should be cited as third-party clinical background for the ingredient category and concentration.
Why it is useful for global marketing
The US setting, expert grading plus instrumental measurement, and inclusion of people with sensitive skin and skin of color make its demographics relevant to global markets.
Connection to mechanism
Visible enlarged pores are driven mainly by sebum output and follicular keratinization/plugging. The following nanovesicular RAL study provides mechanistic support for this direct endpoint.
This is the strongest single reference for a pore claim involving a 0.1% retinal product: US-based, peer reviewed, and inclusive of sensitive skin and skin of color.
Source: J Drugs Dermatol 2024 (PMID 39496127)
PORE IMPROVEMENT · MECHANISTIC BASIS
Nano-encapsulated RAL reduces sebum and comedones—the mechanistic chain for pore improvement
−23.6%
Decrease in sebum after 4 weeks with 0.05% RAL nanovesicles (Sebumeter)
Kim 2021 · J Cosmet Dermatol (South Korea; identified)Twenty-three participants with mild-to-moderate acne were studied for 4 weeks. Closed and open comedones decreased significantly at weeks 2 and 4 (P<0.05); sebum fell from 327.95 to 250.65 μg/cm²; scaling index declined; and no irritation occurred. Follicle-penetrating vesicles delivered RAL to the pilosebaceous unit—the anatomical site where comedones and enlarged pores arise.
International comedolytic evidence from France
Morel 1999 (Clin Exp Dermatol; multicenter RCT, n=74): 0.1% RAL gel + 4% erythromycin significantly improved comedones and microcysts (P=0.005), with excellent local tolerability.
Poli 2005 (Dermatology; double-blind, vehicle-controlled, multicenter): 0.1% RAL / 6% glycolic acid significantly reduced papules, pustules, and comedones from month 1; at month 3, overall improvement was about twice that with vehicle (86.1% vs 58.8%).
Retinoid-class corroboration: A tazarotene 0.1% RCT (n=563) showed significantly better pore-size outcomes than vehicle at week 12. A 2025 network meta-analysis of 23 RCTs / 3,905 participants confirmed that topical retinoids significantly improve fine lines, providing the highest evidence tier for the pathway.
Claim linkage: Comedone clearance and normalization of follicular keratinization are recognized routes to visibly smaller pores; the RAL-specific data above provide direct support.
Sources: Kim 2021 (PMID 34587353); Morel 1999 (PMID 10564319); Poli 2005 (PMID 15724103); Lin 2025 (PMID 40707570)
QUANTITATIVE SUMMARY
Magnitude of efficacy improvements reported across studies
Figure 2. Improvements from baseline reported in human clinical studies. Gold = pore/sebum endpoints (required focus); navy = wrinkle/texture/pigment/elasticity endpoints.
Sources: Brown 2023; Cordero 2011, Kim 2021, Kwon 2018, Rouvrais 2018 (J Cosmet Dermatol); J Drugs Dermatol 2024
ADDITIONAL EFFICACY EVIDENCE
Texture · elasticity · pigmentation · redness · tolerability
Skin texture and roughness
Kwon 2018 (double-blind RCT, South Korea): texture improved 13.7% with 0.1% and 12.6% with 0.05%, measured by Antera 3D. Rouvrais 2018: 0.1% RAL cream improved texture more than professional glycolic-acid peels (between-group P=.0252).
Elasticity / firmness / dermal density
Diridollou 1999: epidermal thickness and skin elasticity increased significantly (P<0.01). Deda 2026: comprehensive gains in dermal density and elasticity R2 +11.6–12.8% at 24 weeks. Brown 2023: elasticity +13.9% and firmness +5.6% in 28 days.
Hyperpigmentation and tone evenness
Kwon 2018: melanin index declined significantly only in the 0.1% group (−6.5%). JDD 2024 (US): hyperpigmentation improved 19% (P<0.0001; 47% skin of color). Cordero 2011: pigmentation scores decreased 31–34% over 90 days.
Redness and rosacea-prone skin
Vienne & Ochando 1999 (Dermatology): redness and swelling decreased in 75% of 23 participants with rosacea. Gold 2026: erythema improved significantly from week 2. Differentiated positioning: “a retinoid suitable for sensitive, redness-prone skin.”
Tolerability and safety
Fluhr 1999 (n≈355): retinoic acid caused significantly more erythema/scaling than retinaldehyde, whose irritation approached placebo levels. Sachsenberg-Studer 1999 (n=357) confirmed tolerability and absence of phototoxicity. Recent studies reported zero adverse events in the MLV-RAL RCT; Deda 2026 observed irritation in only 1/56 and no thinning of the stratum corneum.
Activity against C. acnes
Pechère 2002 (Dermatology): retinaldehyde showed direct antibacterial activity against C. acnes, attributable to its aldehyde group; retinol and retinoic acid did not. This provides supplementary mechanistic support for the pore/comedone narrative.
Sources: Kwon 2018; Diridollou 1999; JDD 2024; Vienne & Ochando 1999; Fluhr 1999 (PMID 10473963); Pechère 2002
DELIVERY-SYSTEM RATIONALE
Why retinal benefits from liposomal / nano-encapsulated delivery
Retinal is intrinsically photolabile and readily oxidized, making stability and controlled release central formulation challenges. Authoritative reviews state that nanoformulations—liposomes, multilamellar vesicles, niosomes, solid lipid nanoparticles, and nanostructured lipid carriers—can simultaneously improve retinoid stability, skin penetration, and irritation profiles.
Human evidence for encapsulated retinal spans four delivery technologies: multilamellar vesicles (Kim 2021), liposomes (Brown 2023), niosomes (Kim 2021), and biomimetic exosomes (Gold 2026). All reported efficacy comparable or superior to non-encapsulated comparators with good tolerability.
Preclinical delivery data
- Pisetpackdeekul 2016 (Int J Nanomedicine): chitosan-grafted “pro-retinaldehyde” nanoparticles improved stability, enabled sustained release, and reduced irritation. In a split-face comparison, 0.025% retinaldehyde nanoparticle hydrogel outperformed 0.025% tretinoin hydrogel on texture parameters in aged skin.
- Limcharoen 2020 (ACS Biomater Sci Eng): the same platform achieved sustained delivery, epidermal proliferation/differentiation activity, and follicular penetration.
- Nayak 2018 (J Drug Targeting): a nanostructured lipid carrier co-loading coenzyme Q10 and 0.05% retinaldehyde produced significant in-vivo anti-wrinkle effects with a better safety profile.
Follicular penetration directly supports pore positioning: vesicular carriers deliver retinal to the pilosebaceous unit, where comedones and enlarged pores arise. PuriPharm NanoActive® RAL was developed using this nano-encapsulated retinal approach and directly builds on the human and preclinical delivery evidence above.
Sources: Milosheska & Roškar 2022 (Adv Ther); Zhong 2024 (J Cosmet Dermatol 10.1111/jocd.16415); Pisetpackdeekul 2016; Limcharoen 2020; Nayak 2018
PROPRIETARY EFFICACY VALIDATION
Four-week human efficacy test of NanoActive® RAL serum
Sponsor: Huzhou PuriPharm Biomedical Technology Co., Ltd. · Testing laboratory: Intertek (Shanghai; report CRS-2020-PR-01) · Product: nano-encapsulated retinal serum · Single-center, open-label, before-and-after study · All 30 participants completed (Chinese women; mean age 49.0, range 38–55) · Whole-face use twice daily for 4 weeks · Instruments: PRIMOS 3D wrinkle analysis and Skin-Colorimeter CL400 · No adverse events
Instrumental results (baseline W0 → week 4 W4)
| Site / instrument | Parameter | W0 mean | W4 mean | Improvement | P value |
|---|---|---|---|---|---|
| Crow’s feet (PRIMOS) | Count | 273.87 | 188.83 | −31.05% | <0.001*** |
| Area (%) | 18.16 | 15.90 | −12.45% | <0.001*** | |
| Length (μm) | 218.20 | 191.77 | −12.11% | <0.001*** | |
| Forehead wrinkles (PRIMOS) | Count | 360.87 | 261.00 | −27.67% | <0.001*** |
| Area (%) | 18.54 | 16.32 | −11.98% | <0.001*** | |
| Length (μm) | 311.90 | 288.07 | −7.64% | <0.001*** | |
| Skin tone (CL400) | L* value | 59.10 | 60.63 | +2.59% | <0.001*** |
| ITA° value | 31.35 | 35.11 | +12.02% | <0.001*** |
Participant self-assessment (n=30)
- Overall satisfaction 96.7%
- Firmer, more elastic skin 93.3%
- Brighter tone / improved radiance 93.3%
- Gentle and non-irritating 93.3%
- Finer, smoother skin 90.0%
- Improved under-eye fine lines 90.0%
- Whitening effect 83.3%
Source: Intertek test report CRS-2020-PR-01 (2020-10-30); all instrumental improvements P<0.001 (***); sponsor: Huzhou PuriPharm Biomedical Technology Co., Ltd.
CORE EVIDENCE TABLE
Core human clinical evidence table (selected studies; full version in report Table 1)
| Study (journal) | Design | n | Region | RAL concentration | Key efficacy result |
|---|---|---|---|---|---|
| Creidi 1998, JAAD | Double-blind RCT | 125 | France | 0.05% | Significant improvement in wrinkles/roughness by profilometry from week 18; better tolerability than retinoic acid |
| Cordero 2011, J Cosmet Dermatol | Open multicenter | 1,462 | International | 0.05% | Crow’s feet −27%; perioral −34%; elasticity +32–33% at 90 days |
| Rouvrais 2018, J Cosmet Dermatol | RCT vs peels | 55 | France | 0.1% | Crow’s-feet depth −7.61% at 8 weeks; comparable with glycolic peels; superior texture outcome |
| Brown 2023, Dermatol Ther | Clinical + in vitro | 32 | Spain/EU | Liposomal 0.1% | Wrinkle count −43.2% at 28 days; crow’s feet decreased in 100% |
| JDD 2024, J Drugs Dermatol | Open instrumental | 32 | US | 0.1% | Pores +20% (P<0.0001) at 8 weeks; fine lines +12%; pigmentation +19% |
| Deda 2026, J Cosmet Dermatol-indexed | Double-blind split-face | 56 | Poland | 0.1% vs 0.05% | Significant wrinkle improvement with 0.1%; comprehensive rise in dermal density at 24 weeks |
Six representative studies are shown. The complete 19-study evidence table—including labels for Korean studies, multicomponent finished products (†), and tolerability—appears in Section 7 of the report.
All studies were published in peer-reviewed international journals; PMID / DOI links are provided in the report.
CLAIM RECOMMENDATIONS
Evidence-supported cosmetic claim language
| Claim area | Suggested cosmetic-compliant wording | Supporting evidence |
|---|---|---|
| Anti-wrinkle | Helps reduce the appearance of fine lines and wrinkles | ≥10 human studies, including 4+ RCTs; Creidi 1998, Rouvrais 2018, Brown 2023; proprietary 4-week Intertek study (crow’s feet −31.0%) |
| Pore refinement | Visibly improves the appearance of pores; helps reduce excess sebum and unclog pores | JDD 2024 (direct endpoint); Kim 2021 niosome; Morel 1999 / Poli 2005 (comedones) |
| Texture / elasticity / even tone | Improves skin texture and firmness; helps promote a more even-looking skin tone | Kwon 2018, Diridollou 1999, Cordero 2011, JDD 2024 |
| Redness / sensitive skin | Suitable for sensitive and redness-prone skin | Vienne & Ochando 1999; Gold 2026; Fluhr 1999 (tolerability) |
Application note
All studies used finished products containing 0.05–0.1% retinal. NanoActive® RAL falls within this window. Claim validation should reuse instrumental endpoints from the cited trials, such as Antera 3D and Sebumeter.
Full sources and qualifying conditions for each claim are provided in Section 8 of the report.
COMPLIANCE AND LIMITATIONS
Considerations when using this evidence package
- Multicomponent finished-product studies (marked † in the report): Some high-value studies tested multicomponent finished products. Their results support the ingredient category and concentration, not independent attribution to a specific raw material. Cite them as third-party technical background and state that in-vitro data do not represent finished-product clinical efficacy.
- Acne-treatment language: Treatment claims in trials by Morel, Poli, Dréno, and others must be softened in cosmetic jurisdictions to language such as “blemish-prone skin” and “helps unclog pores.”
- South Korean studies: Two Korean studies are clearly identified. If a client requires non-Asian evidence only, French, Polish, Spanish, and US studies still form a complete anti-wrinkle and pore narrative in the core evidence table.
- Positioning of proprietary data: The 4-week Intertek test of NanoActive® RAL serum (n=30) was a single-center, open-label, before-and-after study and can serve as proof of concept for finished-product efficacy. For a higher evidence grade, upgrade to a randomized, controlled, 8–12-week instrumental study using Antera 3D + Sebumeter + Cutometer. The Deda 2026 and JDD 2024 protocols provide publication-grade templates that can be reused.
Detailed compliance language and disclaimers are provided in Section 8 and in the final statement of the report.
CONCLUSION
Retinal: more than 30 years of clinical evidence focused on pore improvement and anti-wrinkle efficacy
- Anti-wrinkle: ≥10 human studies and 4+ RCTs, fully covering the 0.05–0.1% concentration window.
- Pores: A direct US JDD 2024 endpoint (+20% at 8 weeks), supported by mechanistic evidence for reduced sebum and comedones with nanovesicles.
- Encapsulated delivery: Human studies across four carrier technologies show comparable or superior efficacy with good tolerability.
- Proprietary validation: In a 4-week Intertek test of NanoActive® RAL serum (n=30), crow’s-feet count fell 31.0%, forehead-wrinkle count 27.7%, and ITA° increased 12.0% (all P<0.001), with no adverse events.
PuriPharm Co., Ltd. · NanoActive® RAL nano-encapsulated retinal · PuriActives® efficacy ingredient seriesThis material is a scientific literature compilation supporting cosmetic-ingredient development. It summarizes third-party published research for technical reference only and does not constitute proprietary clinical data, medical advice, or evidence for medicinal claims. Clients should verify the applicability of every claim and citation under the regulations of their target markets.
© 2026 PuriPharm Co., Ltd. · Retinal Clinical Efficacy Evidence Review