Prebiotics, probiotics and postbiotics: what really works, and what is just beauty marketing?

Based on numerous expert studies on skincare, it is no longer enough to ask which active ingredient to apply to one’s skin; instead, one must consider how a product will affect the ecosystem already living on the skin.

The skin is a complex biological ecosystem in which billions of microorganisms—bacteria, fungi, viruses, and others—interact daily with one another and with our body's cells. The microbiome plays a role in maintaining the skin barrier, regulating the immune system, and protecting against potential pathogens. For this reason, prebiotics, probiotics, and postbiotics are becoming increasingly important in dermocosmetics.

However, there is a significant difference between a scientifically promising concept and a product that simply bears the word "microbiome" on its packaging.

It is essential to understand the specific functions of—and the differences between—these three terms: prebiotics, probiotics, and postbiotics.

What are prebiotics?

A prebiotic is a substrate—essentially food—for specific host microorganisms, and it can thus have a beneficial effect on our health. In the context of skincare, the concept is promising. Instead of "adding" bacteria to the skin, the aim is to create conditions that help the skin's existing microorganisms thrive. This approach relies on modulating the skin's pre-existing ecosystem.

However, caution is warranted here. The evidence supporting topical prebiotics is not yet as robust as the marketing hype surrounding the concept. Earlier studies on this topic had already warned that the clinical efficacy of topical prebiotics was insufficiently researched, whereas more recent papers show growing interest and promising results—though there remains a need for higher-quality clinical studies.

 It is important to know “which” microorganism truly gains a selective advantage, using “which” substrate and under “what” conditions.

What are probiotics?

Probiotics are live microorganisms that, when administered in adequate amounts, can confer health benefits to the host. Can such microorganisms be beneficial when applied to the skin? The concept seems simple enough.

However, incorporating live microorganisms into cosmetic formulations presents a significant technological challenge. They must survive the manufacturing process, preservatives, pH levels, temperature fluctuations, storage conditions, and exposure to oxygen, all while remaining stable enough to retain biological activity at the time of use.

Consequently, many products marketed as "probiotic" do not necessarily contain live, clearly defined, and clinically tested probiotic strains. A recent review of studies from 2026 highlights specific issues regarding viability, stability, compatibility with preservatives, and the regulation of probiotic formulations.

What are postbiotics?

Postbiotics are preparations consisting of non-viable microorganisms and/or their components that can exert a beneficial biological effect. It is not necessary to apply live bacteria to the skin to harness the specific molecules and metabolic byproducts they produce. This offers practical advantages, such as improved formulation stability and the elimination of issues associated with maintaining live microorganisms.

For this reason, postbiotics have become a subject of great interest in dermatology in recent years. An analysis of 16 studies from 2026 regarding topical postbiotics for acne, eczema, and rosacea showed improvements in the skin barrier, as well as a reduction in inflammation and specific symptoms associated with these conditions.

What does the latest literature say?

One particularly interesting finding comes from a 2026 systematic review that analyzed 33 clinical studies involving a total of 2,112 patients with acne. The analysis covered the oral and topical use of prebiotics, probiotics, and postbiotics over periods ranging from 4 to 25 weeks. The results showed a reduction in total lesions with the use of these preparations. The conclusion was that the use of prebiotics, probiotics, and postbiotics is safe and that they play a role as an adjunctive therapy. They cannot replace standard dermatological acne treatment but represent a potential "new layer of therapy." Interestingly, research is shifting focus away from the simple question of "how many bacteria we have" toward "which species and strains are present, what they produce, and how they interact with the skin."

 And what about beauty marketing?

 The word "microbiome" on packaging is not, in itself, proof of clinical efficacy. It is not enough for a product to feature terms like "probiotic complex," "microbiome technology," "fermented ingredients," "good bacteria," or "prebiotic complex" for us to conclude that it alters the microbiome in a clinically significant way. To seriously evaluate a product, several questions should be asked:

 - Which microorganism or metabolite was used?

-  Was a specific strain identified?

-  Is the microorganism live, or is it a lysate, ferment, or postbiotic?

- Are there clinical studies involving humans?

- How long did the research last?

It is important to note that "microbiome-friendly" is not yet a standardized medical category. The skin microbiome is not something that should be sterilized, nor is it something that should be indiscriminately nourished or populated. The goal of modern microbiology is not to increase the number of microorganisms, but to preserve the functional balance of the skin ecosystem. The future of dermocosmetics will likely lie in a more precise approach:

Specific strain - specific metabolite - specific metabolism - specific patient

Based on this, we can expect the development of personalized formulations that take into account the microbiome, skin barrier function, inflammatory status, age, skin region, and the specific dermatological condition. This essentially represents the path from microbiome-inspired skincare to precision dermatology.