Efficacy of Probiotic Supplements and Topical Applications in the Treatment of Acne: A Scoping Review of Current Results

Introduction

Acne vulgaris is one of the most prevalent dermatological conditions globally, affecting individuals across diverse age groups and socioeconomic backgrounds.¹ This multifactorial disorder is characterized by the formation of comedones, papules, pustules, and, in severe cases, nodules and cysts. Furthermore, acne vulgaris significantly impacts both physical appearance and psychological well-being.² Despite the contribution of various factors to its pathogenesis, recent studies show the relationship between skin microbiome and acne development.^3,4

Skin, a complex ecosystem hosting a myriad of microbial communities, plays an important role in maintaining cutaneous homeostasis.⁵ However, perturbations in this delicate balance, termed dysbiosis, have been implicated in acne pathophysiology.³ Propionibacterium acne, now recognized as Cutibacterium acne (C. acne), has been a subject of particular interest due to the association with inflammatory acne lesions.⁶ A previous study observed alterations in the relative abundance of other commensal and pathogenic bacteria in acne-affected skin, suggesting a broader dysregulation of skin microbiota.⁷

According to previous studies, the efficacy of current antibiotic treatments for acne has diminished due to increased resistance and reduced effectiveness,^8,9 leading to a shift toward novel treatment methods. Probiotics, live microorganisms known for conferring health benefits when administered in sufficient quantities, have surfaced as promising agents in rebalancing the microbiome and alleviating symptoms.^3,4 These probiotics have garnered increasing attention for the potential to modulate skin microbiota and mitigate inflammatory skin conditions, including acne vulgaris.¹⁰

While the benefits of probiotics have been extensively studied, concerns about potential side effects remain. Some studies have reported mild gastrointestinal discomfort, such as bloating or diarrhea, in individuals consuming certain probiotic strains.¹¹ However, the systemic absorption of probiotics applied topically is minimal, suggesting a lower risk of adverse effects.¹² Additionally, clinical trials examining the use of probiotics for acne management have shown minimal safety concerns, further supporting their potential as adjunctive therapies.¹³

Despite the evidence supporting the plausibility of probiotics as adjunctive therapeutic agents in acne management, a comprehensive evaluation of the efficacy, optimal strains, dosages, and mechanisms of action remains essential. This evaluation consolidates existing evidence from randomized controlled trials (RCT) or clinical studies to assess the potency of probiotics in enhancing microbiome balance and ameliorating acne vulgaris. Therefore, this study aimed to elucidate the potential of probiotics as a promising avenue for future treatment in modulating skin microbiome to alleviate acne-related manifestations.

Methods

A comprehensive search was conducted across PubMed, Scopus, and Cochrane, using keywords, such as “probiotic”, “microbiome”, “acne vulgaris”, “clinical trial”, and “randomized controlled trial” to identify relevant studies. The Boolean operators were adopted, using “OR” to expand the scope within each concept and “AND” to refine the search for pertinent results, aiming to capture a broad and focused selection of relevant studies. All original studies and clinical reports published from 2009 to 2024 regarding the use of probiotics in acne management were included. The inclusion criteria were original studies with RCT designs, as well as interventional and clinical studies investigating the efficacy of probiotics for acne treatment. Exclusion criteria were abstracts from conference proceedings, case reports, commentaries, editorials, and study protocols. Figure 1 shows a detailed selection process of studies.

Figure 1 The flowchart of the study selection process.

The collected information included authorship, methods, country, population/sample size, intervention, study design, duration, and results regarding the role of probiotics in acne vulgaris. The results were analyzed, using a structured method to derive meaningful conclusions. Descriptive statistics were used to delineate the prevalence of specific study characteristics. The results were presented narratively, with extensive discussions to ensure the precision and reliability of the conclusions.

Results

The searches conducted on MEDLINE, Scopus, and Cochrane found 461, 164, and 97 records, respectively, and 722 registers. After eliminating 651 duplicates, 71 records were screened and 40 were identified for full-text assessment. In the final review, 15 studies were included. The selection process is shown in Figure 1 of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart.

Clinical studies collectively enrolled 811 subjects, with each sample size ranging from 20 to 112 per study. Most studies focused on subjects with mild to moderate acne. However, a few trials included more severe forms, such as inflammatory acne or papular pustular rosacea. The age of the subject varied widely, ranging from 12 to 62 years old.

The types of probiotics used in these studies were diverse, covering both oral and topical formulations. Oral probiotics included strains, such as Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus salivarius, Lactobacillus acidophilus, Lactobacillus delbrueckii subspecies bulgaricus, Bacillus indicus, Bacillus subtilis, Bacillus coagulans, Bacillus licheniformis, Bacillus clausii, Escherichia coli Nissle, the cyanobacterium Arthrospira platensis, Bifidobacterium bifidum, Bifidobacterium breve. Meanwhile, topical probiotics included strains, such as Lactobacillus paracasei, Lactobacillus acidophilus, Lactobacillus salivarius, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus pentosus, Enterococcus faecalis, Enterococcus faecalis and Bifidobacterium animalis. Some trials combined probiotics with conventional treatments, such as benzoyl peroxide, isotretinoin, or minocycline.

The experimental periods varied, typically ranging from 4 to 12 weeks, with most studies measuring outcomes at intervals, namely 4, 8, or 12 weeks. Some studies also included shorter treatment periods, such as the 30-day intervention in Ukraine or the 4-week study conducted in Korea. The summaries of the studies on probiotics for acne vulgaris were presented in Tables 1 and 2 for oral and topical probiotics, respectively.

Table 1 Efficacy of Oral Probiotic Use in Acne Vulgaris Patients

Table 2 Efficacy of Topical Probiotic Use in Acne Vulgaris Patients

Discussion

Acne is a multifactorial skin condition affecting millions globally, particularly during adolescence and adulthood. This condition arises from factors, such as excess sebum production, clogged pores, bacterial overgrowth, and inflammation.²⁷ Conventional treatments of acne, including antibiotics, retinoids, and benzoyl peroxide, are often effective but may lead to side effects, such as skin irritation and antibiotic resistance.^28–30 In recent years, probiotics have become an alternative and complementary option in acne treatment, promising fewer side effects while promoting skin health.

Probiotics are live microorganisms that confer health benefits by balancing microbial populations when consumed or applied to skin.^31,32 The mechanisms by which oral and topical probiotics address acne vulgaris differ but complement one another. Oral probiotics primarily function through the gut-skin axis and restore balance to the gut microbiome, reducing systemic inflammation that can increase the condition of acne^33,34 By promoting the growth of beneficial bacteria, such as Lactobacillus and Bifidobacterium species, oral probiotics help decrease the levels of pro-inflammatory cytokines and regulate immune responses, indirectly benefiting skin health. This reduction in systemic inflammation often leads to less sebum production and fewer acne lesions.²¹ Meanwhile, topical probiotics function directly on skin by modulating the local microbiome. These probiotics compete with pathogenic bacteria, such as C. acne, reducing overgrowth and inflammation at the site of acne lesions. Topical probiotics enhance skin barrier function, increase hydration, and reduce irritation, creating a healthier environment for skin to heal.^20,35

The most commonly used probiotics for acne vulgaris treatments are from the Lactobacillus strain, followed by Bacillus, Bifidobacterium, Enterococcus, and Escherichia coli. Lactobacillus strains were the most prevalent in the studies, showing substantial improvements in acne severity and skin condition. For instance, a study conducted in Korea showed that Lactobacillus plantarum CJLP55 significantly reduced acne lesions and improved skin hydration, enhancing skin lipid barrier.³⁶ Lactobacillus rhamnosus SP1 decreased Insulin-like Growth Factor 1 (IGF-1) levels and enhanced the expression of Forkhead Box O1 (FOXO1),¹⁷ suggesting a modulation of insulin signaling pathways that may be relevant in acne pathogenesis.³⁷ Elevated insulin levels, often due to resistance, can increase the production of androgens (male hormones), thereby stimulating sebaceous glands to produce more sebum. Excess sebum can clog hair follicles, producing a conducive environment for the growth of C. acne, a key contributor to inflammation.²⁴ The study conducted in Spain showed that Lactobacillus rhamnosus and Arthrospira platensis caused significant reductions in inflammatory lesions.³⁸ This result showed the role of Lactobacillus in improving acne symptoms through both immune modulation and skin health enhancement.³⁴

In topical administration, a study from Taiwan showed that topical formulation containing a combination of Lactobacillus strains improved the moisture score of skin and reduced inflammation.²⁵ This result supports the idea that topical probiotics may enhance skin barrier function and reduce acne-related inflammation directly at the site of application.^15,20 Moreover, the study from China featuring topical lotion containing ferment lysate from Lactobacillus plantarum showed significant improvements in acne lesions and reduced sebum production.³⁹ This result suggests that topical probiotics can exert direct effects on skin, improving local conditions and enhancing healing processes.

Previous studies using Bacillus strains showed positive effects on acne treatment. USA (United States of America) study found that oral supplementation with these probiotics decreased sebum excretion rates and also improved gut permeability markers, suggesting a systemic effect on skin health.⁴⁰ This result shows the potential of Bacillus probiotics to influence both local and systemic factors contributing to acne. However, this Bacillus strain has not been tested for topical administration.

In the context of Bifidobacterium, the study from Italy showed the effectiveness of probiotic formulation containing Bifidobacterium breve. The results showed a significant reduction in inflammatory lesions compared to control groups.⁴¹ This suggests that Bifidobacterium strains may also play a crucial role in acne management, possibly through the modulation of the gut-skin axis. The strains help maintain a balanced gut microbiome, producing short-chain fatty acids (SCFAs) that possess anti-inflammatory properties, enhance intestinal barrier integrity, and reduce systemic inflammation connected to acne.^42,43 Additionally, these strains modulate immune responses, influence hormonal regulation related to insulin and androgens, and produce metabolites that support skin barrier function and hydration.^22,26 The gel preparation containing Bifidobacterium combined with Lactobacillus strains has been shown to improve the moisture score of skin in vivo, reduce the inflammation index, and accelerate the healing of acne-related wounds.²⁵ It also diminished the appearance of brown patches and porphyrins on the face, which are connected to acne.²⁵ The mechanism behind this effect includes the ability of probiotics to enhance skin barrier by promoting ceramide production, which improves hydration and reduces transepidermal water loss (TEWL).^16,34 Additionally, probiotics modulate the immune response, reducing pro-inflammatory cytokines. In vitro, studies showed that this combination effectively suppressed the growth of C. acne, reduced pro-inflammatory cytokines, such as thymic stromal lymphopoietin (TSLP) and interleukin-33 (IL-33), and enhanced wound healing in human keratinocyte (HaCaT) cell cultures.²⁵

Enterococcus faecalis was used in two studies, both showing the ability to improve acne lesions when applied topically. The first study showed significant improvement scores on the treated side compared to the control. However, the treatment success rate did not show a significant difference.¹⁴ The second study showed a marked reduction in inflammatory lesions with topical application of Enterococcus faecalis SL-5.¹⁸ The mechanism of action is believed to include the production of bacteriocins by Enterococcus faecalis, which target and reduce the population of C. acne, a key contributor to inflammation. This probiotic can modulate local immune responses by reducing the release of pro-inflammatory cytokines and promoting an anti-inflammatory environment, leading to reduced lesion formation and inflammation.^14,18 Meanwhile, in a study conducted in Ukraine, Escherichia coli Nissle contributed to significant improvement in acne outcomes alongside dietary changes. This result shows the potential of Escherichia coli to modulate skin health through the gut microbiome.¹⁹

In general, these trials show the potential of probiotics, either topically or orally, to significantly reduce acne lesions and inflammation, improve skin health, and restore a healthy skin microbiome. However, some showed comparable efficacy to conventional treatments, such as benzoyl peroxide and antibiotics. These results suggest that probiotics could be a safe and effective alternative or adjunct to conventional acne treatments.

Despite the promising effects of probiotics on acne treatment, there are potential side effects and limitations that should be considered. Some individuals may experience mild gastrointestinal discomfort, such as bloating or diarrhea, especially with oral probiotics, though these effects are typically transient and resolve with continued use.¹¹ Topically, while probiotics are generally well-tolerated, allergic reactions or skin irritation may occur in sensitive individuals.¹² Additionally, the variability in individual responses to different probiotic strains poses a challenge in determining the most effective formulation for acne treatment.²³ The need for further research to standardize dosages, strains, and administration methods is crucial to minimize these side effects and maximize the therapeutic benefits of probiotics in acne management. Furthermore, while probiotics may be beneficial for mild to moderate acne, their role in severe cases, where inflammation and bacterial resistance are more pronounced, remains uncertain and requires additional investigation.

Conclusion

In conclusion, the use of probiotics, both oral and topical, showed great promise as a treatment for acne. Oral probiotics modulated the gut microbiome and reduced systemic inflammation. Meanwhile, topical probiotics offered a direct, gentler method to balanced skin microbiome and reduced acne lesions. Advancements in studies showed that probiotics could become a mainstream treatment option for acne, offering a natural and effective alternative to conventional treatments. However, more standardized study was necessary to determine the most effective probiotic strains, combinations, and treatment regimens for different types of acne. While most studies highlighted the positive effects of probiotics, some limitations, such as strain-specific efficacy and variability in individual responses, must be addressed. Furthermore, the role of probiotics in managing severe acne requires additional investigation to assess their utility as an adjunctive therapy alongside conventional treatments.