The skin microbiome — what it is and what it means for your routine.

The skin microbiome is a topic that has moved rapidly from academic dermatology into consumer skincare marketing. Products now claim to "balance," "nourish," and "protect" the microbiome. Some of these claims are well-grounded; others are not. Understanding what the skin microbiome actually is, what it does, and what research currently supports makes it easier to evaluate both.

What the skin microbiome is

The skin microbiome is the community of microorganisms — bacteria, fungi, viruses, and archaea — that inhabit the skin's surface and its appendages (follicles, sweat glands). The number of microbial cells on the skin is in the billions, varying considerably by body site. The face, particularly the nose and forehead, is sebum-rich and has its own characteristic microbial composition. The forearm is drier and less diverse. The groin and armpits are warm and occluded with yet different communities.

The dominant genus on most areas of healthy skin is Cutibacterium (formerly Propionibacterium, present in sebaceous areas), Staphylococcus (on both dry and moist sites), and Corynebacterium (on moist areas). Malassezia fungi are universal residents of sebum-rich areas.

What the microbiome does

Competes with pathogens. Commensal (resident) bacteria occupy physical space and consume resources, limiting the ability of harmful microorganisms to establish. Staphylococcus epidermidis, a commensal resident, produces antimicrobial peptides that inhibit Staphylococcus aureus, a pathogen associated with eczema flares and wound infections.

Supports the acid mantle. Commensal bacteria metabolise sebum components and produce short-chain fatty acids that contribute to the skin's slightly acidic pH. This acidity is itself antimicrobial and provides a hostile environment for many pathogens.

Communicates with immune function. Skin immune cells interact continuously with the microbiome. These interactions influence immune tolerance — the skin's ability to distinguish harmless microorganisms from genuine threats. A disrupted microbiome is associated with increased inflammatory responses to otherwise tolerable triggers.

Contributes to odour regulation. The axillary microbiome metabolises sweat components into odorous compounds. Microbial community composition influences body odour more than sweat output alone.

The microbiome and skin conditions

Several common skin conditions are associated with changes in the skin microbiome — though the relationship between cause and effect is not always clear.

Acne. Cutibacterium acnes is implicated in inflammatory acne, but it is also present on the skin of people without acne. The relationship is complex: it is the immune response to certain strains of C. acnes — not the bacterium alone — that drives inflammation. Microbiome diversity may be a more relevant factor than C. acnes presence.

Eczema (atopic dermatitis). Associated with reduced microbial diversity and an overgrowth of Staphylococcus aureus, which can further disrupt the barrier and amplify inflammation. Restoring barrier function appears to support microbiome normalisation — the direction of causality is the subject of ongoing research, but treating the barrier rather than trying to manipulate the microbiome directly is better supported.

Seborrhoeic dermatitis. Associated with an overgrowth of Malassezia fungi in susceptible individuals. Antifungal treatments targeting Malassezia are among the most evidence-backed interventions for this condition.

What disrupts the microbiome

Alkaline cleansers. A pH above the skin's natural 4.7–5.5 disrupts the environment that supports commensal bacteria and inhibits pathogen growth. Alkaline soap-based cleansers have been shown to reduce commensal bacterial diversity and temporarily increase surface pH in ways that may affect microbial composition over time.

Antibiotics — topical and oral. Broad-spectrum topical antibiotics (clindamycin, erythromycin) reduce C. acnes but also affect other commensal species. Oral antibiotics affect the gut microbiome, which has bidirectional signalling with the skin (the gut-skin axis), with effects that are not fully characterised.

Excessive cleansing frequency. Multiple daily washes, particularly with stripping cleansers, reduces microbial diversity and removes the sebum that many commensals depend on for nutrition.

Alcohol-dominant toners and astringents. High concentrations of alcohol disrupt the lipid layer and the commensal bacteria that inhabit it.

What the evidence supports for microbiome care

The most consistent finding in microbiome research is that a healthy barrier supports a healthy microbiome — not the reverse. A barrier that maintains its pH, lipid composition, and structural integrity provides the ecological conditions that commensal bacteria require. Disrupting the barrier disrupts the microbiome.

This means that the most evidence-supported approach to microbiome care is not the addition of probiotic or prebiotic skincare products — which have limited independent clinical evidence for specific microbiome modification — but the protection of the barrier conditions that allow a healthy microbial community to maintain itself.

Low-pH, non-alkaline cleansing maintains the acid mantle that the microbiome depends on. Avoiding over-cleansing and over-exfoliation preserves the microbial diversity that aggressive protocols reduce. A barrier-supporting moisturiser reinforces the conditions that keep the skin's ecology in balance.

A note on probiotic and prebiotic skincare. Products containing live bacteria (probiotics) or bacterial nutrients (prebiotics) are a growing category, but the evidence for significant, durable microbiome modification through topical application is limited. Many bacterial strains do not survive in a cosmetic formulation; those that do may not colonise the skin in meaningful numbers. The category is promising and research is ongoing, but it is not yet at the level where specific product recommendations can be made confidently.

The Lux & Glo approach

The ritual was not designed around the microbiome directly. It was designed around the barrier — gentle cleansing at the right pH, ceramide synthesis, lipid reinforcement. The microbiome benefits are indirect and a consequence of the same principle: support what the skin already does, rather than overriding it.

A cleanser that does not raise the skin's pH. A serum that builds ceramides from within. A moisturiser that reinforces the lipid matrix. All of these create the conditions the microbiome needs without attempting to manage it directly — which, given the current state of evidence, is the more defensible position.