"Pennyroyal is a plant. The leaves, and the oil they contain, are used to make medicine. Despite serious safety concerns, pennyroyal is used for the common cold, pneumonia, fatigue, ending a pregnancy (abortion), and as an insect repellant, but there is no good scientific evidence to support these uses. In manufacturing, pennyroyal oil is used as a dog and cat flea repellent, and as a fragrance for detergents, perfumes, and soaps."