How Scientists Study the Scalp Microbiome
Before looking at what the scalp microbiome does, it helps to understand how we know about it at all.
The scalp microbiome is an active area of research, studied using modern sequencing and metagenomic methods across a range of populations and study designs.
Microbial Balance and the Concept of Dysbiosis
Flaking-type scalp presentations are conceptually linked to a shift in the balance among these microbes — often described as dysbiosis — rather than to any single organism acting alone.
This framing — balance versus imbalance — underpins much of how scalp microbiome science is discussed.
Sebum, Malassezia, and Scalp Irritation
Mechanistically, Malassezia yeasts metabolize scalp sebum, and this metabolic activity is thought to contribute to irritation and flaking.
Oiliness is part of this ecological picture: research comparing oily and non-oily, dandruff and non-dandruff scalps has observed differing microbial compositions.
Barrier Function and Microbial Ecology
Microbes don't act in isolation — they interact with the physical structure of the scalp itself.
Scalp barrier function (such as transepidermal water loss and lipid composition) and microbial ecology are conceptually interrelated, with barrier changes and microbial shifts potentially influencing one another.
The Hair Follicle as a Distinct Microbial Habitat
Scalp hair follicles form distinct, deeper niches compared to the surface skin, suggesting the follicular environment may be a separate microbial habitat worth practitioner awareness.
Why This Matters for Practitioners
None of this is about diagnosing a client — it's about understanding the ecology behind what you're observing.
What this page can — and cannot — tell you
Scope: This page is intended as a conceptual overview for beauty and scalp-care practitioners, describing general scalp microbiome composition, the balance/imbalance (dysbiosis) concept, and its conceptual relationship to flaking and oiliness and to barrier function. It does not provide diagnostic criteria, treatment protocols, medication or probiotic recommendations, or specific clinical outcome statistics, and it excludes content centered on specific diagnosed conditions (e.g., alopecia subtypes, Malassezia folliculitis, psoriasis) beyond general conceptual mention.
Causal relationships between scalp microbes and hair-follicle cycling or immune processes remain largely hypothesized rather than firmly established.
Much of the evidence comes from relatively small, observational studies that demonstrate association rather than proven cause-and-effect relationships.
Observed microbial differences between healthy and flaking scalp groups often show relatively small effect sizes, indicating host and environmental factors also play a substantial role.
Several foundational studies were conducted in specific populations or were industry-funded, which may limit how broadly the findings generalize.
Key takeaways
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01
The scalp hosts a community of bacteria (such as Cutibacterium/Propionibacterium acnes and Staphylococcus epidermidis) and fungi (notably Malassezia species such as M. globosa and M. restricta), together referred to as the scalp microbiome.
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Flaking-type scalp presentations are conceptually linked to a shift in the balance among these microbes — often called dysbiosis — rather than to any single organism acting alone.
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03
Mechanistically, Malassezia yeasts metabolize scalp sebum, and this metabolic activity is thought to contribute to irritation and flaking.
Sources & references
The cleared source set supporting this page's evidence review.
- Thomas L. Dawson Jr.. Malassezia globosa and restricta: Breakthrough Understanding of the Etiology and Treatment of Dandruff and Seborrheic Dermatitis through Whole-Genome Analysis
- Cécile Clavaud, Roland Jourdain, Avner Bar-Hen, Magali Tichit, Christiane Bouchier, Florence Pouradier, Charles El Rawadi, Jacques Guillot, Florence Ménard-Szczebara, Lionel Breton, Jean-Paul Latgé, Isabelle Mouyna. Dandruff Is Associated with Disequilibrium in the Proportion of the Major Bacterial and Fungal Populations Colonizing the Scalp
- Rituja Saxena, Parul Mittal, Cécile Clavaud, Darshan B. Dhakan, Prashant Hegde, Mahesh M. Veeranagaiah, Subarna Saha, Luc Souverain, Nita Roy, Lionel Breton, Namita Misra, Vineet K. Sharma. Comparison of Healthy and Dandruff Scalp Microbiome Reveals the Role of Commensals in Scalp Health
- Katarzyna Polak-Witka, Lidia Rudnicka, Ulrike Blume-Peytavi, Annika Vogt. The role of the microbiome in scalp hair follicle biology and disease
- M.B. Lousada, T. Lachnit, J. Edelkamp, T. Rouillé, D. Ajdic, Y. Uchida, A. Di Nardo, T.C.G. Bosch, R. Paus. Exploring the human hair follicle microbiome
- Le Deng, Xiao Ling, Li Li, Youjie He, Miaomiao Guo. Advances in Scalp Microbiome Research: Molecular Insights into the Metabolism-Inflammation-Barrier Axis and Dandruff Pathogenesis
- Giulia Galizia, Anna Belloni Fortina, Alessandra Semenzato. Seborrheic Dermatitis: From Microbiome and Skin Barrier Involvement to Emerging Approaches in Dermocosmetic Treatment
- Jyoti Gupta, Amit Arora, Sunil Dogra, Arunaloke Chakrabarti, Archana Angrup, Sendhil Kumaran, Harsimran Kaur, Anup K Ghosh, Shivaprakash M Rudramurthy. Malassezia and Staphylococcus are associated with scalp seborrheic dermatitis
- Andrea Izdebska, Adriana Błaszczyk-Windak, Ewelina Knapczyk, Wiktoria Turczyn. Interplay between microbiome, immunity, and skin barrier in seborrheic dermatitis
- Roland Jourdain, Alain Moga, Philippe Vingler, Charles El Rawadi, Florence Pouradier, Luc Souverain, Philippe Bastien, Nicolas Amalric, Lionel Breton. Exploration of scalp surface lipids reveals squalene peroxide as a potential actor in dandruff condition
- Taehun Park, Hye-Jin Kim, Nu Ri Myeong, Hyun Gee Lee, Ilyoung Kwack, John-Hwan Lee, Byung Jun Kim, Woo Jun Sul, Susun An. Collapse of human scalp microbiome network in dandruff and seborrhoeic dermatitis
- Rohan R. Shah, Jorge Larrondo, Thomas Dawson, Amy McMichael. Scalp microbiome: a guide to better understanding scalp diseases and treatments
- Rong Tao, Ruoyu Li, Ruojun Wang. Skin microbiome alterations in seborrheic dermatitis and dandruff: A systematic review
- Akira Vorapreechapanich, Arsa Thammahong, Tanittha Chatsuwan, Steven W. Edwards, Chanat Kumtornrut, Karaked Chantawarangul, Susheera Chatproedprai, Siriwan Wananukul, Direkrit Chiewchengchol. Perturbations in the skin microbiome of infantile and adult seborrheic dermatitis and new treatment options based on restoring a healthy skin microbiome
- Han Yu, Jiayi Li, Yan Wang, Tongze Zhang, Tahir Mehmood, Olivier Habimana. Dysbiosis and genomic plasticity in the oily scalp microbiome: a multi-omics analysis of dandruff pathogenesis