NOW Foods Organic Oregano Oil is a 100% pure essential oil steam-distilled from certified organic Origanum vulgare — providing the same high-carvacrol therapeutic oil found in popular oil of oregano supplements, but in pure essential oil form for aromatic and topical use. Carvacrol and thymol are the primary active phenolic compounds responsible for oregano oil's powerful antimicrobial reputation, demonstrated in numerous in vitro studies against a wide range of bacteria and fungi. The certified organic designation ensures the herb was grown without synthetic pesticides or herbicides — important for an oil used near skin or in enclosed diffused spaces. GC/MS tested by NOW Foods to verify carvacrol content and purity. Oregano essential oil is very potent — always dilute heavily (1-2% maximum) in carrier oil before any skin contact. Not for internal use.