Dandruff is often described simply as “dry scalp.” Current research, however, shows that visible flaking is more complex and cannot be reduced to a single cause. Microorganisms living on the scalp, sebum and its breakdown products, epidermal barrier function, inflammatory responses and individual susceptibility may all contribute.
For that reason, statements such as “dandruff means too much Malassezia” or “an oily scalp directly causes dandruff” are incomplete. A more accurate approach is to view the scalp as an ecosystem.
What Is Dandruff?
Dandruff is characterized by visible scaling and flaking of the scalp and may be accompanied by itching. It shares some mechanisms and symptoms with seborrheic dermatitis, but not every case of dandruff is seborrheic dermatitis. Marked redness, significant inflammation, thick crusting, sores or persistent severe itching should be evaluated by a dermatologist.
What Is Malassezia?
Malassezia is a group of lipid-dependent yeasts that can naturally live on human skin and scalp. Its presence alone does not mean disease. In current dandruff and seborrheic dermatitis research, Malassezia restricta and Malassezia globosa are among the species frequently studied.
When Malassezia metabolizes lipids in sebum, compounds including free fatty acids can be produced. In susceptible individuals, these metabolites may interact with barrier and inflammatory responses and contribute to flaking or discomfort. Because Malassezia can also be found on healthy scalp, however, “Malassezia = dandruff” is not an accurate equation.
Three Important Factors: Microbial Activity, Sebum and Individual Susceptibility
One long-standing model of dandruff emphasizes the interaction of three components:
- Microbial activity: particularly Malassezia species and the broader composition of scalp microorganisms.
- Sebum and the lipid environment: because Malassezia is lipid-dependent, sebum is an important part of scalp microbial ecology.
- Individual susceptibility: barrier integrity, immune and inflammatory responses, genetics and personal sensitivity can make the same microbial environment behave differently from one person to another.
This helps explain why some people with oily scalps have little visible dandruff while others may experience flaking without extreme oiliness.
How Is the Scalp Microbiome Related to Dandruff?
The scalp ecosystem includes more than Malassezia. Cutibacterium, Staphylococcus, Corynebacterium and other microorganisms are also part of this environment.
A 2025 study reported shifts in the microbial profile as dandruff severity increased, including lower levels of Cutibacterium acnes and higher levels of Staphylococcus capitis, Corynebacterium species and Malassezia restricta in more severe dandruff. These findings support an association between the microbiome and dandruff severity, but they do not by themselves prove which changes are causes and which are consequences.
For the broader biology of this ecosystem, read our What Is the Scalp Microbiome? guide.
Why Does the Scalp Barrier Matter?
The outer layer of the scalp acts as a barrier that limits water loss and helps protect against environmental factors. Dandruff-prone scalp has been associated with impaired barrier function, increased irritant sensitivity and inflammatory changes.
Dandruff should therefore not be viewed only as “dead skin buildup.” Flaking is better understood together with changes in epidermal turnover, barrier function and inflammatory processes.
Does an Oily Scalp Cause Dandruff?
Sebum is a normal part of scalp physiology and is not something that should be eliminated completely. Its amount and composition can, however, influence the environment available to lipid-dependent Malassezia species.
There can therefore be a biological relationship between oiliness and dandruff, but there is no simple rule that “more oil always means more dandruff.” Individual susceptibility, microbial composition and barrier responses modify the relationship.
Is pH the Cause of Dandruff?
pH is one parameter considered in hair and scalp product formulation. Current evidence does not support assigning one universal ideal pH number to every scalp or claiming that a rise in pH automatically causes Malassezia overgrowth and dandruff.
Likewise, the presence of SLS or SLES in a shampoo does not by itself prove that the product makes the scalp alkaline or damages the microbiome. Product pH and scalp effects depend on the complete formulation.
How Can You Build a Cosmetic Routine for Dandruff-Prone Scalp?
The role of cosmetic care is not to treat disease. Its role is to cleanse the scalp appropriately, remove excess oil and product residue, and support a comfortable, cared-for scalp appearance.
1. Clean regularly according to scalp needs
There is no single washing frequency that suits everyone. Oil production, styling products, physical activity and personal comfort all matter. Washing less often is not automatically healthier, and unnecessarily aggressive cleansing is not a better routine either.
2. Focus on a balanced-looking oil profile, not eliminating sebum
The current formula of Mirissa Lab Sulfate-Free Salt-Free Scalp Shampoo contains Zinc PCA as a cosmetic ingredient used to support a balanced-looking oil/sebum profile. Lactobacillus Ferment Lysate and Inulin are also included as complementary ingredients in a microbiome-focused scalp-care approach.
3. Support scalp comfort
Panthenol, Betaine, Bisabolol and Aloe Vera are included to support a moisturized, comfortable and cared-for scalp feel. The shampoo does not contain SLS or SLES.
The presence of these ingredients does not mean that the product treats Malassezia, acts as an antifungal medicine or medically eliminates dandruff. Mirissa Lab shampoo is a cosmetic care product.
Explore Mirissa Lab Scalp Shampoo →
Are Dandruff and Hair Loss the Same Thing?
No. Dandruff and hair loss are separate topics. Significant scalp inflammation and some dermatological diseases can occur together with hair shedding, but ordinary dandruff does not automatically mean follicle damage or an early shift into the telogen phase.
Sudden or marked shedding, patchy hair loss, scalp pain, sores or persistent inflammation should be assessed by a dermatologist rather than self-treated with cosmetic products alone.
Dandruff vs. Seborrheic Dermatitis
Dandruff is generally a milder condition dominated by scalp flaking and sometimes itching. Seborrheic dermatitis can involve more obvious redness and inflammation alongside oily or dry scaling, and other seborrheic areas such as the eyebrows, face or ears may also be affected.
The two conditions can share mechanisms, but seborrheic dermatitis may require diagnosis and treatment and should not be reduced to a cosmetic shampoo claim.
Frequently Asked Questions
Is Malassezia the main cause of dandruff?
Malassezia is an important factor, but it is not the only one. The sebum/lipid environment, barrier function, inflammatory responses, other microorganisms and individual susceptibility also matter.
Should Malassezia be completely eliminated?
No. Malassezia can also live on healthy human skin. The scalp is not meant to be sterile.
Does an oily scalp always mean more dandruff?
No. There is a biological relationship between lipids and Malassezia, but dandruff severity is not determined by sebum amount alone.
Does sulfate-free shampoo treat dandruff?
No. Being free from SLS/SLES describes part of the cleansing system; it does not by itself mean antifungal treatment or dandruff therapy.
Will “balancing the scalp microbiome” cure dandruff?
The microbiome is relevant to dandruff research, but without finished-product clinical evidence it is not appropriate to claim that a cosmetic product “rebalances the microbiome and cures dandruff.”
Conclusion
Dandruff is a multifactorial scalp condition that cannot be reduced to one microorganism or one pH value. Current evidence supports important roles for Malassezia and microbial composition while also pointing to sebum metabolism, barrier integrity, inflammatory responses and individual susceptibility.
For cosmetic care, the most defensible approach is appropriate cleansing, a routine that supports scalp comfort and a balanced-looking oil profile, and dermatological evaluation when symptoms are persistent or severe.
Scientific References
- Advances in Scalp Microbiome Research: Molecular Insights into the Metabolism-Inflammation-Barrier Axis and Dandruff Pathogenesis. 2026. PMID: 42357491.
- Dandruff scalp microbiome exhibits flake severity and sex-related differences. Br J Dermatol. 2025. PMID: 41118316.
- Current Understanding of Seborrheic Dermatitis: Epidemiology, Burden of Disease, and Pathophysiology. 2025. PMID: 40965103.
- Scalp microbiome: a guide to better understanding scalp diseases and treatments. 2024. PMID: 39073596.
- More yeast, more problems?: reevaluating the role of Malassezia in seborrheic dermatitis. 2024. PMID: 38472524.
- Three etiologic facets of dandruff and seborrheic dermatitis: Malassezia fungi, sebaceous lipids, and individual sensitivity. PMID: 16382685.
This content is for informational purposes. Mirissa Lab products are cosmetic care products and do not replace medical diagnosis or treatment.
