Causes of Dandruff
Dandruff is primarily caused by the lipophilic yeast Malassezia (formerly known as Pityrosporum), which metabolizes sebaceous lipids, producing irritating free fatty acids that lead to scalp flaking and itching in susceptible individuals. 1, 2
Primary Causes
Malassezia fungi: These commensal yeasts naturally present on the scalp metabolize sebum, releasing free fatty acids (particularly oleic acid) that irritate the scalp in susceptible individuals 2
Sebaceous gland activity: Excessive sebum production provides more substrate for Malassezia, contributing to dandruff development 2
Individual susceptibility: Not everyone with Malassezia on their scalp develops dandruff, indicating that personal sensitivity to fungal metabolites plays a crucial role 2
Stratum corneum dysfunction: Disruption of the scalp's protective barrier leads to impaired hydration, atypical epidermal proliferation, and increased susceptibility to Malassezia metabolites 3
Contributing Factors
Age and gender: Dandruff prevalence and severity is greatest in young men, with children and older individuals affected less frequently 1
Environmental factors: Changes in humidity, seasonal variations, and emotional stress can aggravate dandruff symptoms 1
Physical trauma: Scratching the scalp can worsen dandruff by further disrupting the skin barrier 1
Hair products: Hair sprays, gels, and other styling products can contribute to buildup and irritation 1
Pathophysiological Mechanism
Lipid metabolism: Malassezia breaks down sebaceous triglycerides into free fatty acids, particularly oleic acid, which irritates the scalp 2
Barrier dysfunction: The dandruff-affected scalp shows depleted and disorganized structural lipids, leading to elevated transepidermal water loss 3
Inflammatory response: Subclinical inflammation occurs in response to Malassezia metabolites and contributes to scaling and itching 3
Accelerated cell turnover: Normal scalp skin cells mature and are shed over approximately 30 days; in dandruff, this process is accelerated, leading to visible flaking 3
Differential Diagnosis
Seborrheic dermatitis: A more severe form of dandruff affecting not only the scalp but also other sebaceous areas of the body 2
Tinea capitis: A fungal infection that can present with diffuse scaling resembling dandruff, particularly the "diffuse scale" variant 4
Psoriasis: Can affect the scalp with scaling that might be confused with severe dandruff 5
Atopic dermatitis: May present with dry, scaling skin on the scalp, especially in children 4
Contact dermatitis: Allergic reactions to hair products can cause scaling and irritation similar to dandruff 4
Management Implications
Antifungal agents: Shampoos containing antifungal ingredients like ketoconazole (Nizoral), selenium sulfide, or zinc pyrithione effectively reduce Malassezia populations 6, 2
Barrier repair: Treatments that improve stratum corneum integrity while providing antifungal activity may be particularly beneficial 3
Regular cleansing: Daily shampooing with longer lathering periods helps control dandruff by removing excess sebum and scale 1
Avoidance of aggravating factors: Reducing use of styling products and managing stress can help minimize dandruff flares 1
Specialized formulations: Shampoos with combined properties of oil control, moisturizing, anti-fungal, and itch-relieving ingredients show significant efficacy in reducing both flaking and pruritus 7