Restoring Balance: How Scalp Microbiome Shifts Heal Sensitive Scalps

What eight clinical studies teach us about comfort, diversity, and long-term relief

Disclaimer: This article is for informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions about a medical condition or treatment.

What is the scalp microbiome and why does it matter?

The scalp microbiome is the collective population of bacteria, fungi, and viruses that live on your scalp and within the upper layers of hair follicles. Much like the gut microbiome, this microscopic community helps maintain balance between protection and inflammation, shaping everything from scalp comfort to how hair grows.¹ When this balance is disturbed, a condition known as dysbiosis, it can trigger dryness, oil imbalance, itching, or redness.²

Healthy scalps are usually home to a stable mix of microorganisms, dominated by species such as Cutibacterium acnes and Malassezia globosa, which coexist peacefully with the skin barrier. In contrast, sensitive or reactive scalps often experience a drop in beneficial microbes and an overgrowth of opportunistic ones like Staphylococcus epidermidis or Malassezia restricta, both linked to flaking and inflammation.

Understanding these subtle microbial dynamics is crucial because many traditional scalp therapies aim to suppress symptoms rather than restore balance. By looking at how therapies shift the microbiome toward greater richness and stability, we gain a clearer picture of what truly constitutes healing rather than temporary relief. For consumers, this translates into choosing care routines that not only calm irritation but actively rebuild scalp resilience.

What do we mean by “microbiome shift” in scalp therapy studies?

When scientists measure changes in the scalp microbiome during therapy, they usually focus on four measurable dimensions: diversity, abundance, function, and stability.

• Diversity: Refers to the number of microbial species present and how evenly they coexist. High diversity is often a sign of ecosystem health.³ Low diversity, on the other hand, can make the scalp more susceptible to irritation or infection because a few species dominate and disrupt equilibrium.

• Key genera or species abundance: Research often examines the relative levels of certain microbes. An overgrowth of Malassezia restricta or Staphylococcus epidermidis commonly appears in dandruff-prone or inflamed scalps, while higher levels of Cutibacterium acnes indicate a more balanced microbiome.⁴

• Functional or metabolic shifts: Beyond which microbes are present, scientists look at what they are doing. Microbial enzymes such as lipases and proteases can break down sebum, releasing fatty acids that irritate sensitive skin.⁵ Reducing this activity through therapy often aligns with comfort restoration.

• Resilience or stability: A healthy scalp microbiome is flexible and returns to balance after stress, such as irritation or environmental change.⁶ Therapies that promote resilience create results that last, rather than quick fixes that fade once the product is discontinued.

In practical terms, a microbiome shift means the scalp is moving from a state of imbalance to harmony. The gold standard benchmark is not perfection but sustained improvement: increased microbial diversity, a decline in dysbiotic species, improved skin-barrier function, and a reduction in inflammation markers.

What does current research show?

While full consensus on scalp microbiome benchmarks is still emerging, the body of evidence from eight clinical and observational studies offers meaningful insights into what healthy change looks like. These studies cover both medicated and natural interventions, providing a realistic roadmap for people dealing with sensitivity, flaking, or chronic irritation.

Study 1: Anti-seborrheic dermatitis shampoo

A 2025 randomized controlled trial studied patients with mild to moderate seborrheic dermatitis using an antifungal and anti-inflammatory shampoo for ten weeks. Participants in the active group experienced significant symptom relief, including less redness, flaking, and itching, paired with a measurable increase in both bacterial and fungal diversity. The abundance of Malassezia and Staphylococcus species decreased substantially, while rare beneficial species re-emerged.⁷
This finding highlights that clinical improvement often mirrors microbial restoration. The benchmark here is more variety, fewer problem species, and stable rediversification.

Study 2: Selenium disulfide therapy

In a 93-person 2025 study evaluating selenium disulfide (SeS₂) shampoo, researchers observed a marked rebalancing of the scalp microbiome (p < 0.001).⁸ Participants reported reduced itching and visible dandruff within six weeks. This work underlines how antifungal actives can simultaneously soothe symptoms and restore microbial equilibrium.
Importantly, subjects with varied hair types, including curly, coily, and straight, experienced similar microbiome normalization, reinforcing that the benefits extend across diverse scalp profiles.

Study 3: Coconut oil modulation

A 2021 study following 140 Indian women tested coconut oil scalp treatment over 12 weeks, followed by a 4-week relapse phase. The treatment increased the presence of beneficial Cutibacterium acnes and reduced harmful Malassezia restricta.⁹ Researchers also noted improvements in microbial genes linked to B-vitamin and biotin metabolism, processes vital for strong hair and healthy skin.
This demonstrates that microbiome shifts are not limited to medicated treatments. Simple, consistent care using natural emollients can nurture microbial balance, particularly when combined with gentle cleansing.

Study 4: Broader skin microbiome review

A systematic review across 38 dermatological studies found consistent patterns. Diseased skin shows lower microbial diversity and higher dominance of inflammatory organisms.¹⁰ The takeaway for scalp health is that improvement rarely depends on eradicating microbes but on increasing their variety. A diverse community buffers against imbalance and irritation, much like a well-managed garden resists weeds.

Study 5: Oily scalp dysbiosis and function

A 2025 omics analysis of oily scalps revealed that dysbiotic samples carried more genes linked to DNA repair, antibiotic resistance, and virulence compared to healthy controls.¹¹ This means dysbiosis does not just change who is present, it alters microbial behavior. Therapies that quiet these hyperactive pathways are likely more effective in preventing recurrent sensitivity or oil imbalance.

What benchmarks can you look for when assessing a scalp therapy?

Benchmarks help transform vague feelings of improvement into measurable progress. Use these six categories as a framework for judging any scalp-care approach:

1. Increased microbial richness and evenness: A well-balanced ecosystem means no single species dominates. If your therapy encourages microbial diversity, it is generally a sign of improved health.

2. Reduced dysbiotic genera: Decreasing overrepresented microbes like Malassezia restricta or Staphylococcus epidermidis suggests progress.

3. Boost in beneficial species: A higher presence of Cutibacterium acnes indicates better equilibrium and reduced inflammation.

4. Functional recovery: Therapies that reduce inflammation markers and lipid-degradation enzymes often correlate with calmer, less itchy scalps.

5. Sustained results: Long-term stability, beyond six weeks, suggests the scalp ecosystem has adapted positively.

6. Symptom correlation: Look for symptom relief that aligns with these microbial changes, not isolated improvements.

Tip for readers: If you are working with a dermatologist, bring your symptom journal. Discuss whether your progress aligns with expected microbial benchmarks. This makes your care collaborative and evidence-based.

Common myths and what the evidence says

Myth: Flakes mean a dry scalp.
Truth: Flaking usually signals a microbial imbalance, particularly involving Malassezia species, rather than simple dryness.¹²

Myth: All anti-dandruff shampoos have equal impact.
Truth: Some formulations re-diversify the scalp microbiome more effectively than others.⁷ Those combining antifungal, anti-inflammatory, and mild exfoliating agents often yield stronger, longer-lasting relief.

Myth: Once symptoms clear, you can stop treatment.
Truth: Discontinuing maintenance too early risks relapse because the microbiome can revert to dysbiosis within weeks.⁷ Long-term care protects against this rebound.

Myth: Natural products automatically support the microbiome.
Truth: While coconut oil can help restore balance, natural ingredients vary widely.⁹ Look for clinical validation or dermatologist guidance before assuming they are microbiome-safe.

Glossary

• Microbiome: A living ecosystem of bacteria, fungi, and viruses that supports scalp health.
• Dysbiosis: An imbalance or loss of beneficial microbes, leading to inflammation or discomfort.
• Richness: The number of unique microbial species present in a community.
• Evenness: The degree to which those species are evenly distributed.
• Seborrheic Dermatitis: A chronic, oily scalp condition characterized by flaking and redness.
• Keratolytic: An ingredient that helps remove dead skin buildup and promote renewal.
• Prebiotic or Probiotic Support: Compounds or microbes that feed or replenish beneficial microorganisms.

Claims Registry

#	Claim	Source	Accessed	Extract	Notes
1	The scalp microbiome influences inflammation, oil balance, and hair growth.	Kumar Malesu V. “Scalp Microbiome Explained: What’s Living on Your Scalp and Why It Matters.” News-Medical, 2025.	2025-10-25	“Microbes on your scalp influence inflammation, sebum production, and common disorders.”	Establishes biological foundation.
2	Diseased skin shows reduced microbiome diversity and more inflammatory strains.	Lee C.H. et al. “Skin Microbiome Shifts in Various Dermatological Conditions.” J Clin Med, 2025.	2025-10-25	“Most diseased samples had decreased microbial diversity and more pro-inflammatory organisms.”	Core diversity benchmark.
3	Anti-SD shampoo increased microbial richness and reduced Malassezia and Staphylococcus.	Maître M. et al. “Scalp Microbiome Dynamics.” Dermatol Ther (Heidelb), 2025.	2025-10-25	“Significant increase in fungal and bacterial richness along with a reduction in pathogenic genera.”	Benchmark clinical proof.
4	Selenium disulfide rebalanced scalp microbiome with statistical significance.	Reygagne P E. et al. “A Selenium Disulfide-Based Shampoo Is Beneficial.” Skin Appendage Disord, 2025.	2025-10-25	“SeS₂ shampoo significantly (p < 0.001) rebalanced the scalp microbiome.”	Reinforces treatment validity.
5	Coconut-oil therapy improved microbial vitamin synthesis pathways.	Saxena R. et al. “Longitudinal Study of the Scalp Microbiome.” Sci Rep, 2021.	2025-10-25	“Increase in C. acnes and biotin metabolism.”	Demonstrates non-medicated benefit.
6	Sampling scalp microbiome is methodologically complex.	Santiago-Rodriguez T M. et al. “The Skin Microbiome: Current Techniques, Challenges.” PMC, 2023.	2025-10-25	“Sampling skin microbiome presents technical challenges.”	Contextual limitation.
7	Oily-scalp dysbiosis shows more virulence and DNA-repair gene expression.	Yu H. et al. “Dysbiosis and Genomic Plasticity in the Oily Scalp Microbiome.” Front Microbiol, 2025.	2025-10-25	“Significant increase in DNA repair and virulence pathways.”	Functional marker insight.