Dandruff (Seborrheic Dermatitis): Causes, Triggers, OTC Treatments, and Prevention

Dandruff is mild seborrheic dermatitis of the scalp — flaking, itching, without significant inflammation. Affects ~50% of adults.

Pathophysiology

• Malassezia spp. (lipophilic yeast) metabolize sebum triglycerides → oleic acid (irritant) → inflammation → hyperproliferation → corneocyte clumping (flakes).
• Host susceptibility: skin barrier defect, immune response, sebum composition.

Triggers

• Stress, cold/dry weather, infrequent shampooing, oily skin, neurologic conditions (Parkinson's, stroke), HIV.

OTC Treatments (Active Ingredients)

• Zinc pyrithione (ZPT): Antifungal, anti-inflammatory (Head & Shoulders).
• Ketoconazole 1% (Nizoral): Potent antifungal; 2% Rx.
• Selenium sulfide 1% (Selsun Blue): Antifungal, cytostatic; can discolor hair.
• Coal tar: Antiproliferative, anti-inflammatory; odor/staining.
• Salicylic acid: Keratolytic (removes scale).
• Ciclopirox olamine: Antifungal/anti-inflammatory.

Prevention

• Regular shampooing (daily if oily; 2–3×/week if dry).
• Leave shampoo on 5 min before rinsing.
• Manage stress, healthy diet (zinc, B vitamins, omega-3).
• Avoid harsh styling products, hot water.

When to See a Dermatologist

Severe inflammation, hair loss, facial/body involvement (seborrheic dermatitis), treatment failure → Rx topical steroids, calcineurin inhibitors, oral antifungals.