The skin microbiome — the community of bacteria, fungi, viruses, and other microorganisms that live on skin — is one of the most important and most recently understood dimensions of skin health. Research over the last decade has established that the skin microbiome plays active roles in immune function, pathogen exclusion, inflammation regulation, and barrier maintenance that go far beyond what was previously attributed to skin alone.
The soap you use every day has a direct effect on this microbiome. Understanding that effect clarifies why soap choice matters beyond the marketing claims on the label.
The Skin Microbiome: What It Is and What It Does
Human skin hosts approximately one trillion microorganisms across its surface area. The composition varies dramatically by body region — sebaceous (oily) areas like the face and upper back harbor different communities than dry areas like the forearms, and moist areas like the groin and underarms host different communities still.
The dominant bacteria on healthy skin include species from the genera Cutibacterium, Staphylococcus, Corynebacterium, and Micrococcus. These are not pathogens — they are commensal organisms that earn their place on skin by performing functions that benefit the host:
Pathogen exclusion through competitive exclusion. Commensal bacteria occupy the niche that would otherwise be available to pathogens. Staphylococcus epidermidis, for example, produces compounds that inhibit Staphylococcus aureus colonization. Healthy microbiome composition makes it harder for pathogenic bacteria to establish.
Immune education. The skin immune system develops and calibrates its responses partly through interaction with the microbiome. A diverse microbiome teaches the skin immune system to distinguish harmless commensal bacteria from genuine threats. Disrupted microbiomes — with reduced diversity — are associated with increased rates of inflammatory skin conditions including eczema and psoriasis.
Barrier support. Commensal bacteria produce short-chain fatty acids and other compounds that support the acidic pH of the skin's acid mantle. The acid mantle is maintained partly by skin cells and partly by microbial metabolic activity. Disrupting the microbiome reduces the microbial contribution to acid mantle maintenance.
What Soap Does to the Microbiome
All soap disrupts the skin microbiome temporarily during and immediately after washing. The surfactants that lift dirt and oil from skin also remove microorganisms. This is both the goal of washing (removing pathogens) and a potential problem (removing beneficial commensals).
The critical question is how completely and how quickly the microbiome recovers between wash events. Research has shown that the microbiome returns to pre-wash composition within hours for most healthy individuals. The more disruption each wash causes — through aggressive surfactants, antimicrobial additives, or pH disruption — the slower this recovery is and the more the chronic microbiome composition shifts.
SLS and microbiome disruption. Sodium lauryl sulfate disrupts cell membranes non-selectively. It damages the membranes of beneficial commensal bacteria as effectively as pathogens. Regular SLS exposure produces cumulative shifts in skin microbiome composition toward less diversity and more resilient but potentially less beneficial species.
Synthetic antimicrobials. Triclosan (now largely banned), benzalkonium chloride, and other synthetic antimicrobials in antibacterial soap products kill bacteria broadly without distinguishing between beneficial and harmful species. Regular use can produce resistant strains and reduced microbiome diversity.
Natural antimicrobials. Tea tree oil, the antibacterial active in our Tea Tree Antibacterial Bar Soap, has antimicrobial activity with a different spectrum than synthetic agents. Research suggests that tea tree oil is less disruptive to overall microbiome diversity than synthetic antimicrobials at equivalent use concentrations — though the microbiome research specific to tea tree soap is still developing.
pH disruption. The temporary pH elevation from soap washing affects which microorganisms recover fastest during post-wash microbiome restoration. Bacteria adapted to lower-pH environments — including many beneficial commensals — may recover more slowly than pH-tolerant species after alkaline soap exposure.
Protecting Your Skin Microbiome
The goal is not to stop washing — it's to wash in ways that minimize collateral disruption to the microbiome beyond what's necessary to clean effectively. Several principles apply:
Use natural soap without synthetic antimicrobials for daily washing. The cleaning action of soap removes pathogens mechanically; synthetic antimicrobials add broad-spectrum bacterial killing that is not necessary and is microbiome-disruptive.
Don't over-wash. The microbiome needs time to recover between wash events. Multiple daily showers with aggressive cleansers don't allow adequate recovery time. One thorough post-training wash is more microbiome-friendly than three less thorough washes.
Cold finish. Cold water is less disruptive to the skin microbiome than hot water. The cold finish that ends our recommended shower protocol is microbiome-supportive as well as therapeutically beneficial for other reasons.
Filtered water. Chlorine in tap water is antimicrobial by design. The same antimicrobial action that makes it safe to drink affects the skin microbiome during showering. Our 15-Stage Filtered Showerhead removes chlorine before it contacts your skin — and before it contacts your skin microbiome.
Beyond Clean, Beyond Ordinary.