Dictamnus is a flowering plant that emits flammable vapor in hot weather. The lemon-scented oil evaporates from its leaves. Dictamnus dasycarpus is widely distributed in Asia, especially in Korea and China, and its stems, leaves, and root bark have been used in oriental herbal medicine for centuries. In Traditional Korean Medicine, this plant treats various ailments, such as skin inflammation, pruritus, eczema, rubella, scabies, acute rheumatoid arthritis, and the common cold. Limonoids from D. dasycarpus root bark show inhibitory action on iNOS and COX-2 expressions, which suggests a potential treatment for inflammatory diseases.