Postbiotics in Dermatology: A Literature Review of Emerging Topical Therapies for Acne, Rosacea, and Eczema

Postbiotics, defined as non-viable microbial cells and their metabolites, have emerged as topical therapies for inflammatory dermatoses and provide more clinical benefits than live postbiotics by eliminating infection risk and stability. This literature review aims to generalise existing knowledge about the effectiveness and mechanisms of action of first-line topical postbiotic treatments for acne, rosacea, and eczema. Search terms included "postbiotics" and keywords that represented the dermatological conditions of interest. Thematic synthesis was performed on the systematically extracted data. After screening, 16 studies were included in the review. Postbiotic preparations showed significant reductions in Scoring Atopic Dermatitis (SCORAD) and pruritus and improved barrier function in the skin, as well as longer remissions (p < 0.001). In acne vulgaris, postbiotics decreased inflammatory lesions by 50% to 70%, suppressed sebum secretion (42% to 72%), and stopped the growth of Cutibacterium acnes. The study concluded that topical postbiotics, reported to be effective in atopic dermatitis and acne vulgaris, have favourable safety profiles and can be integrated into treatment regimens for the aforementioned diseases. However, no interventional studies have examined rosacea, and the evidence is limited to narrative reviews in which microbiome disequilibrium remains undetermined despite a lack of clinical efficacy. Therefore, a lack of clinical trials for rosacea is a high research priority, given the substantial mechanistic rationale for this absence of high-quality pragmatic evidence.

The human skin microbiome is a complex ecological community of commensal bacteria, fungi, and viruses that plays a vital role in maintaining cutaneous health and immune homeostasis [1]. A disruption in this microbial consortium has since been recognised as a decisive pathogenic factor in a continuum of inflammatory dermatoses, including acne vulgaris, rosacea, and atopic dermatitis (eczema) [2]. Traditional treatment approaches have aimed directly at eliminating pathogenic microbes, but this therapy can be more damaging to the normal microbiota, potentially leading to prolonged gut barrier dysfunction and the emergence of antimicrobial resistance [3]. The International Scientific Association of Probiotics and Prebiotics (ISAPP) defines postbiotics as the preparations of nonliving microorganisms and/or their components that have a health benefit for the host. In contrast to live probiotics, postbiotics, such as metabolites, cell-wall fragments, enzymes, and peptides generated during the fermentation of their prebiotic counterparts by probiotics, represent a viable, stable, and non-violent option for clinical usage [4]. They have a complex mechanism of action, including antimicrobial effects against pathobionts, direct anti-inflammatory effects on immune cells and keratinocytes, strengthening the skin barrier, and shaping the resident microbiome, which makes them ideal topical treatment options [5]. The application of postbiotics in dermatology is of particular concern, given the urgent need to develop targeted, safe, and effective therapies for chronic inflammatory diseases [6]. Acne vulgaris, which is caused by the overgrowth of Cutibacterium acnes along with the occurrence of inflammation [7], and eczema, most commonly referring to atopic dermatitis, which is caused by disruption of the barrier and type 2 inflammation [8]. Rosacea is a chronic inflammatory skin disorder primarily affecting the central face, characterised by persistent erythema, flushing, telangiectasia, papules, and pustules. It is associated with vascular dysregulation, immune system dysfunction, and microbial factors and may also involve ocular manifestations (ocular rosacea). Metabolites are produced by probiotic bacteria, such as Lactobacillus [9]. Bifidobacterium species are a potential alternative measure to reduce cutaneous inflammation and prevent the development of pathogenic microbes while preserving homeostasis in the epidermis [10]. This review aims to generalise existing knowledge about the effectiveness and mechanisms of action of first-line topical postbiotic treatments for acne, rosacea, and eczema. The review will examine the interactions of multiple postbiotic ingredients, ranging from fermentation supernatants and isolated peptides, with the cutaneous milieu. It aims to clarify the translational relevance of postbiotics as a foundation for upcoming dermatological therapeutics and to assess their capacity to transform the impact of common dermatoses through microbial metabolites.

Methodology The narrative review was conducted with a search of the literature on three main electronic databases: PubMed, Google Scholar, and the Cochrane Library. Search strategies used controlled vocabularies along with database-specific keywords (with Medical Subject Headings (MeSH) terms included); full search expressions are presented in Table 1. Although it is a narrative literature review, the literature search was conducted systematically using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow chart to ensure transparency and reproducibility. The reviewers included peer-reviewed English articles published between 1 January 2006 and 31 January 2026. Only randomized controlled trials, cohort trials, and review articles that tested postbiotic preparation topically in acne vulgaris, rosacea, or atopic dermatitis were considered eligible, and postbiotic constituents specifically, non-viable bacterial cells or cell lysates or metabolites, and present clinical efficacy (isolated decrease in the count of lesions, amelioration of erythema, changes in Eczema Area and Severity Index (EASI) score) or mechanistic pathways (expression of anti-inflammatory cytokines, antimicrobial activity, improvement of barrier functionality). The process of data extraction was carried out using a pre-specified narrative approach template, which includes data extraction of variables such as author(s), study design, sample characteristics, the specific postbiotic intervention, the comparator, results, and follow-up outcomes. The data collected were later analysed thematically in order to identify universal patterns of action and clinical efficacy across the three dermatology conditions, identify the current literature evidence landscape, and patterns of evidence gaps. Since the review only used published data, no ethical approval or informed consent was required. Selection process of studies The initial database query provided 164 records, including 57 PubMed records, 13 Cochrane Library records, and 94 Google Scholar records. Eighty-seven duplicate records were removed prior to the screening phase. The remaining 77 unique records were screened for title and abstract, resulting in the removal of 43 articles that were evidently unrelated to the research question, such as those on gut health, oral supplementation, or non-dermatological use. The remaining 34 reports were also searched and located with success. Then these 34 reports were evaluated in detail against the eligibility criteria. After this comprehensive review of the full text, 17 reports were also eliminated based on irrelevant outcomes, and one had an irrelevant intervention. Finally, a total of 16 high-quality studies were incorporated in the final qualitative synthesis after meeting all the inclusion criteria (Figure 1). Characteristics Table 2 shows the key features of the 16 studies included in the literature review, and they include research conducted in 12 countries and on three continents. The studies are an uneven mix of methodology designs, with seven randomised controlled trials (RCTs), three longitudinal, two retrospective or pilot before-after studies, and two article reviews. The sizes of samples ranged between 10 and 396 responses, and the population of studies in the dermatological lifespan was indicated (between six months of age in pediatric patients and 70 years of age in adults), hence highlighting the wide applicability of postbiotic interventions to both groups. The geographic location of the research location included multicenter European trials, hospital-related studies in South Korea and China, and clinical trials in India, Indonesia, and Brazil, which represented the interest of the international scientific community in microbiome-based therapy for inflammatory skin diseases. Concerning the dermatological conditions under investigation, eight articles examined acne vulgaris, seven articles examined atopic dermatitis, and two studies provided an extensive overview of the role of the microbiome in rosacea, whereas primary interventional data on rosacea were limited to mechanisms of action as well as narrative reviews. Interventions available in the acne studies included different formulations of postbiotics, includingLactoSporin produced from the homogenate of Enterococcus faecalis; fermented lysates derived from various strains of Lactiplantibacillus plantarum; tyndallized Lactobacillus plantarum; and bacteriocin preparations obtained from strains of E. faecalis. Trials investigating atopic dermatitis were predominantly conducted using formulations containing biomass or lysates of Vitreoscilla filiformis and multi-species-derived postbiotic solutions from Streptococcus. These formulations were applied for treatment durations ranging from four to 15 weeks. Comparators varied across studies and included creams, paraffin-based moisturisers, urea-based emollients, and active pharmaceutical agents such as benzoyl peroxide; however, most single-arm studies relied on baseline comparisons to evaluate therapeutic efficacy. The findings of the review are compared narratively below. However, the quantitative primary outcomes, safety outcomes, and follow-up time points are presented in Table 3. Efficacy of postbiotics in atopic dermatitis The literature is consistent in showing that clinical outcomes are significantly improved in patients with atopic dermatitis treated with topical postbiotic preparations. In Gelmetti et al., it was reported that the mean Scoring Atopic Dermatitis (SCORAD) decreased by 59.2% and the Pruritus Score (PRURISCORE) decreased by 64.1% after 15 weeks of treatment using a Lactobacillus ferment-containing cream, and the effect was much greater in week five itself [11]. In the same vein, Kim et al. demonstrated that an animal-derived postbiotic, which is based on Streptococcal multi-species, was successfully used in the Investigator’s Global Assessment (IGA) in 41.5% of the patients, whereas an animal-based placebo, conversely, achieved results at most 12.1% (p=0.005), as well as with respect to pruritus, skin hydration, and transepidermal water loss (TEWL) [12]. There have always been positive results of the V. filiformis biomass in different types of studies: Seité et al. found that using the active form of the V. filiformis reduced the SCORAD by 11% in the active group and increased the SCORAD by 35% on the comparator side [14], and Gueniche et al. discovered that the use of the active type of the V. filiformis lowered the modified Eczema Area and Severity Index (mEASI) by 42.9% in the active group. These results were further verified by Prakoeswa et al., who found that issues with SCORAD, EASI, and pruritus scores, as well as Dermatology Life Quality Index (DLQI), reduced significantly more after V. filiformis lysate application than when a urea-based moisturiser was used [16]. De et al. offered relevant long-term information that proved that a ceramide-based postbiotic moisturiser had a significantly longer effect, lasting a mean remission of 72.5 days when compared to 47.4 days with a paraffin-based comparator (p=0.0001), as the percentage of complete remission between these two groups had reached 100% during the initial treatment course [13]. Efficacy of postbiotics in acne vulgaris Findings from eight clinical trials suggest that topical postbiotic preparations yield substantial, quantifiable efficacy in acne vulgaris across a wide range of outcome measures. Majeed et al. showed a reduction of 50.02%, 63.11%, and 69.96% of closed comedones, open comedones, and papules, respectively, with a 21-day LesoSporin reduction of 21.45%, 21.66%, and 21.87% in Bacillus coagulans compared with the control, respectively [18]. It was also found that the formulation reduced sebum release by 42.4% (p<0.0001) and was rated as non-irritating in patch testing. Similar findings were obtained with Lactiplantibacillus ferment lysates; Cui et al. reported that in Monte Carlo by week 4, there were significant changes in the proportion of acne lesions, TEWL, and sebum production, and in vitro C. acnes growth was stopped [19]. Similarly, Cui et al. revealed that the proportion of lesions and sebum was significantly lowered using E15 strain lysate and that 72.7% of the test subjects exhibited reduced sebum production in week four [21]. Li et al. have indicated that the formulation of a Lactobacillus fermentation lysate had a reducing effect on Global Acne Grading System (GAGS) scores (more than half, p=0.01) and also had a high content of VISIA parameters, such as speckle, pore, red region, and porphyrin score (85% of patients were satisfied). Han et al. presented evidence from split-face RCTs demonstrating that E. faecalis CBT SL 5 extract produced significantly more clinical benefits than vehicle at weeks 2, 4, and 6, with a significant reduction in phylogenetic diversity of the skin microbiome [24]. According to Tagliolatto et al. [23], 60% of patients achieved more than 50% lesion reduction using tyndallized L. plantarum cream; 90% of adherents rated their therapeutic response as good or very good. Anwar et al. noted a decrease in mean lesion count from 48.5 to 24.5 after the intervention with Lactococcus fermentlysate, but there was no statistically significant change in cytokine [22]. This was shown by Biazzo et al., who reported mechanistic microbiome data, in which good clinical responders to a L. plantarum-containing formulation had stable alpha diversity, higher relative abundance of beneficial Staphylococcus epidermidis, and lower relative abundance of C. acnes compared with non-responders [27]. In all acne research, postbiotic preparations had positive drug safety profiles and few adverse events and therefore may be used as a well-tolerated and safe alternative or adjunct to traditional acne interventions. Current evidence and research gaps in rosacea Unlike the substantial clinical trial evidence for atopic dermatitis and acne vulgaris, the evidence for postbiotic interventions in rosacea is limited to mechanistic reviews and narrative syntheses, with no direct interventional evidence. A wide-ranging review of the microbiome dysbiosis of the pathogenesis of rosacea by Prajapati et al. revealed that the overgrowth of mites of the genus Demodex folliculorum and microbial changes were common in patients with rosacea [25]. The review posits that the cutaneous microbiome may be a new treatment target for postbiotics; however, it clearly states that interventions based on this approach have not been evaluated in clinical trials for rosacea. The dysbiotic environment of rosacea was described similarly by Rušanac et al., who found increased Demodex loads, immunogenic Bacillus oleronius, reduced Roseomonas mucosa, and context-dependent pathogenicity of Staphylococcus erythropathogenes [26]. The authors cited only one case study in which a patient with rosacea responded to low-dose doxycycline with a probiotic preparation of Bifidobacterium breve/Lactobacillus salivarius. Nevertheless, this is a combination therapy rather than a pure postbiotic intervention, and the evidence is at the lowest clinical level. Clinical efficacy of topical postbiotics The therapeutic response of topical postbiotics is durable, with patients experiencing prolonged remission and lower relapse rates than with traditional emollients [13,14]. They are improved by enhanced cutaneous barrier function, as evidenced by reduced TEWL, greater stratum corneum hydration, and a desirable modulation of the skin microbiome, specifically a reduction in pathogenic colonisation by Staphylococcus aureus [12,14,17]. The consistency of these results across studies, including those examining the application of Viteascilla filiformis and Lactobacillus strains conducted in different geographic regions, strengthens the evidence for the use of postbiotics in the treatment of atopic dermatitis. Postbiotic interventions are equivalent to traditional drugs such as benzoyl peroxide for the treatment of acne vulgaris but offer the added benefit of improved tolerability and minimal irritancy [18]. In eight controlled studies, postbiotic preparations resulted in a statistically significant decrease in inflammatory and non-inflammatory lesions and a significant improvement in closed comedones (50-63%), open comedones (63%), and papules (70%). The anti-sebum properties are highly important, as the sebum synthesis decreases 42-72% [18,20,21], which is one of the major pathogenic factors in acne. The clinical observations have been validated with quantitative imaging modalities, such as VISIA and Antera3D, showing a significant reduction in erythema, lesion elevation and porphyrin fluorescence [18,20]. Antibacterial activity against C. acnes was also observed. Compared with that, the postbiotic efficacy in rosacea remains purely preclinical and hypothetical. Although a putative pathophysiological model links microbial dysbiosis, such as overgrowth by the dinoflagellate and Demodex, with the immunogenicity of B. oleronius, to manifestations of rosacea [25,26], there are no RCTs or prospective cohort studies that have tested topical postbiotics specifically in rosacea samples. The available literature comprises narrative reviews and one case report on probiotic combination therapy, which does not permit a substantively meaningful conclusion regarding clinical efficacy. This gap in evidence is particularly noteworthy, given that mechanistically plausible postbiotic candidates with anti-inflammatory and microbiome-modulating properties are available and have been successful in other inflammatory dermatoses. Limitations This literature review has several limitations, including some studies with high attrition rates and insufficient characterisation of postbiotic interventions, as some studies provide no indication of the bacterial strain, fermentation conditions, processing methods, or concentrations of bioactive compounds. Most studies did not follow up long enough to establish the longevity of response or the safety of long-term relapse. A key limitation of this review is the limited number of studies evaluating postbiotics in rosacea compared to acne and eczema. This imbalance restricts the strength and generalisability of conclusions regarding their efficacy in rosacea. Recommendations Considering the identified evidence gaps, several recommendations can inform future studies. Future studies should focus on rosacea, using outcome measures and extended follow-up to assess the strength of the reaction. Second, studies should include a complete description of the bacterial strain, fermentation conditions, inactivation strategy, concentration, and bioactive components, thereby improving reproducibility. Future studies should include the pediatric population, as atopic dermatitis is more common among them.

The study concluded that topical postbiotics demonstrated substantial improvements in severity scores, a balanced profile of inflammatory mediators, increased skin-barrier efficacy, reduced pathogenic microbial colonisation, and an excellent safety and tolerability profile. These findings support the use of postbiotics as a supportive or, at a minimum, complementary component of the treatment plan in the future.