Its association with cooling evident in its scent, peppermint is a fast-growing perennial herb with small white flowers. Peppermint is the primary mint variety used in aromatherapy and its top notes are bright and fresh, while hints of camphor and grass fill out its undertones. One of the most powerful pain relief oils for reducing severe tension headaches, it is also perfect for topical application to muscle pain. Peppermint is a must for clearing head colds and sinus discomfort and it is a useful study aid because it can help to increase mental focus.