Zinc Pyrithione

Zinc pyrithione is an antifungal/antibacterial active commonly used in anti-dandruff and seborrheic dermatitis products (typically ~0.3–2%) and is a recognized cause of irritant contact dermatitis in patch testing, with occasional allergic reactions reported. On facial or eczematous/compromised skin it can sting, burn, and worsen barrier disruption, especially with frequent use or alongside other actives. Given its pharmacologic activity and documented irritation profile, it warrants careful introduction and avoidance on severely compromised skin. Safety Notes: In consumer anti-dandruff shampoos and other rinse-off scalp products, zinc pyrithione has historically been marketed across a broad range, with low-end usage around ~0.01–0.3% in gentle/maintenance formulas and common OTC levels around ~1%. The highest consumer-available OTC products have been observed at 2.0% (the long-standing maximum for OTC dandruff drug shampoos in several markets), while leave-on applications are uncommon and, where present, are typically formulated at lower levels due to sensitization/irritation risk and regulatory restrictions (e.g., EU cosmetic use is prohibited).