Essential Oils and Their Single Compounds in Cosmetics—A Critical Review

The document from 2018 critically reviews the use of essential oils and their compounds in cosmetics, discussing their benefits such as antimicrobial and antifungal properties, as well as their potential side effects like contact dermatitis and allergies. It highlights the importance of proper labeling of potential allergens as mandated by the EU Cosmetics Regulation. The review also notes the variability in essential oil composition due to factors like plant quality and extraction methods, and it mentions studies on the topical effects of oils like rosemary on skin and hair health. Despite the benefits, the review concludes that essential oils can pose allergy risks and should be used with caution in cosmetic products. Specific findings include a retrospective study with 1508 eczema patients where 7.6% had a positive reaction to fragrance allergens, and a 2015 study showing rosemary oil's effectiveness in treating androgenic alopecia with fewer side effects than Minoxidil. Cases of allergic reactions to compounds such as L-carvone, citral, eugenol, farnesol, geraniol, limonene, linalool, and menthol are also discussed. The review ultimately states that while essential oils can cause allergic reactions, they are generally safe for most people when used appropriately in cosmetics.