By Ciobanu Sebastian — Founder & Head of Product, Folliq · Published 27 September 2026
Key Takeaways
- Your scalp carries its own community of bacteria and yeast, dominated by two genera — Cutibacterium and Staphylococcus — living in a slightly acidic environment most people never think about.
- A 2022 study found a measurable difference in scalp bacteria between people with androgenetic alopecia and people without it. The authors were explicit that this shows an association, not proof that the imbalance causes the hair loss.
- The two most common ways people disrupt their own scalp microbiome are over-washing and sulfate-heavy shampoo — both push the scalp's pH away from where these bacteria do their job.
- Nothing Folliq sells is a microbiome treatment, and we're not going to imply otherwise. This article exists because the topic is genuinely relevant to scalp health, not to sell a fix for it.
"Scalp microbiome" has become a phrase skincare brands attach to almost anything. Underneath the marketing, there's a real and fairly young field of research, and it's worth separating what it actually shows from what gets implied by a product label.
What's actually living on a healthy scalp
Every scalp carries a resident community of bacteria and fungi, and in a healthy scalp two bacterial genera dominate it: Cutibacterium and Staphylococcus. A 2025 multi-omics analysis of the scalp microbiome found these two, alongside a third genus called Lawsonella, together made up more than half of the bacterial population sampled — consistently higher here than at most other skin sites on the body.¹
Cutibacterium feeds on sebum and, in the process, helps maintain the scalp's naturally acidic pH — typically cited in the 4.5 to 5.5 range.² Staphylococcus epidermidis produces antimicrobial compounds that keep more opportunistic organisms in check. The yeast Malassezia is part of this same ecosystem too; we've covered what happens when it overgrows in our article on itchy, flaky scalp, so this piece focuses on the bacterial side instead.
None of this is exotic. It's the same logic as the gut microbiome, applied to a different patch of skin: a resident population that, left alone, does useful maintenance work you never notice.
Does an imbalance actually cause hair loss?
This is where the marketing usually gets ahead of the research, so it's worth being precise about what one of the more carefully designed studies actually found.
A 2022 Korean cross-sectional study compared the scalp and gut microbiomes of 141 people — 46 without androgenetic alopecia and 95 with it, split further by sex and severity. Among men, Staphylococcus was significantly less abundant on the scalps of those with androgenetic alopecia than on the scalps of those without it. Among women, a different genus, Bifidobacterium, was significantly more abundant in the alopecia group. The gut microbiome, by contrast, showed no significant difference in overall diversity between the two groups.³
Two things about that result are easy to miss if you only read a headline built from it. First, the pattern differed by sex — this isn't one clean signature that shows up the same way in everyone. Second, and more importantly, the study's own authors describe this as evidence of an association, not proof of causation, and note that their analysis relied on predictive modeling rather than experiments that could establish which direction the relationship runs. A scalp microbiome shift showing up alongside hair loss does not tell you whether the shift caused it, resulted from it, or whether both are downstream of something else entirely — hormonal changes affecting sebum production being an obvious candidate that affects both.
So the honest summary is: there's a real, measurable correlation worth further study, and it is not yet a mechanism anyone has demonstrated, let alone a target anyone has proven you can treat your way to more hair by correcting.
What actually disrupts it, and what doesn't
Whatever the microbiome's exact role in hair growth turns out to be, disrupting it is well understood, and mostly comes down to two ordinary habits.
Sulfate-based shampoos are effective at stripping oil, which is precisely the problem — they don't distinguish between excess sebum and the sebum Cutibacterium needs to maintain scalp pH. Alkaline formulas push pH upward, away from the 4.5–5.5 range these bacteria are adapted to, and that shift alone is associated with more flaking, independent of anything fungal going on.²
Over-washing does the same thing through repetition rather than formula strength — even a mild shampoo used too often keeps resetting the scalp before its own ecosystem re-establishes itself. Neither of these is a Folliq-specific claim; it's consistent dermatology across the scalp-care literature, and it applies regardless of what device or topical you're using on top of it.
What we won't tell you is that any product — ours included — is a microbiome treatment. Nothing in our line is formulated, tested, or marketed as one, and a five-minute daily scalp massage with the Red Light Scalp Massager increases circulation to the area, which is a different mechanism entirely from managing bacterial populations. We mention it once, for exactly what it is, not as a microbiome fix.
What's worth doing, and what isn't yet
Based on what the evidence above actually supports: wash enough to manage visible oil and odor, not on a fixed daily schedule regardless of need; if you use a sulfate shampoo, don't also add other stripping steps on the same day; and treat any dandruff or persistent itch as its own problem, worth the differentiated approach in our itchy scalp article, rather than something a "microbiome" product claims to fix in one step.
What isn't worth doing yet: buying a probiotic scalp spray, a prebiotic shampoo, or any product marketed specifically around "rebalancing" your scalp microbiome as a hair-growth strategy. The research connecting scalp bacteria to hair loss is real and worth watching, but it hasn't reached the point of telling anyone which direction to intervene in, by how much, or with what. A claim that sounds precise — "restores your microbiome for thicker hair" — is outrunning a field that currently can't tell you that with any confidence.
When to see a dermatologist
See a dermatologist rather than experimenting with over-the-counter microbiome products if you have persistent scalp redness, odor, or itching that doesn't resolve with a gentler shampoo routine; if hair loss is sudden, patchy, or accompanied by scarring; or if you've already tried adjusting your washing habits for six to eight weeks without any change in scalp comfort. A clinician can test for infection or seborrheic dermatitis directly rather than guessing from a product label.
Nothing in this article is medical advice and it cannot assess your situation. The Folliq product linked above is a cosmetic product, not a medical device, and is not intended to diagnose, treat, cure or prevent any disease.
References
- Multi-omics analysis of the oily scalp microbiome identifying dysbiosis in dandruff pathogenesis. Front Microbiol. 2025.
- Clinical and in vitro reports on scalp pH, sebum composition, and topicals formulated to preserve the scalp microbiome. J Clin Aesthet Dermatol.
- Jung DR, Yoo HY, Kim MJ, et al. Comparative analysis of scalp and gut microbiome in androgenetic alopecia: A Korean cross-sectional study. Front Microbiol. 2022;13:1076242.