Thyme can be used internally or externally. It is antimicrobial, antifungal, antioxidant, and vermifugal (especially against hookworms.) Thyme has been used for thousands of years as a culinary as well as medicinal herb. It is a common ingredient in mouthwashes and retards plaque formation and gingivitis. You can combine thyme with rosemary, lemon, or tea tree.