Thymus Vulgaris Oil

Thymus Vulgaris (thyme) oil is a highly concentrated essential oil rich in thymol and carvacrol, compounds with well-documented irritant and sensitization potential, even at low leave-on concentrations (often well below 1%). Clinical patch testing and case reports show essential oils are common triggers for allergic contact dermatitis and can markedly flare eczema due to barrier disruption. Given the high risk in sensitive and compromised skin and the potential for delayed sensitization, it warrants a very high irritancy score. Safety Notes: In mass-market leave-on skincare (creams/lotions/serums), Thymus vulgaris (thyme) oil is typically used at very low fragrance/antimicrobial-support levels (often ~0.0005–0.05%) due to sensitization/irritation potential and IFRA-restricted allergen components (e.g., thymol, carvacrol, linalool). Higher consumer-available concentrations are seen in rinse-off cleansing products and some niche “clarifying”/essential-oil-forward spot or scalp treatments, where total thyme oil can reach ~0.2–1.0% while remaining OTC; above ~1% is uncommon in mainstream skincare because odor intensity, dermal tolerance, and IFRA compliance become limiting.