The process of heating (without boiling) a mixture of water and an essential oil (scented liquid taken from a plant) to release a pleasant aroma. Aromatherapy infusion may also refer to the process of heating an herb in liquid to release the essential oils. Inhaled oxygen scented by aromatherapy infusion is being studied as a complementary therapy (used in addition to standard treatments) to relieve pain and shorten recovery time in patients undergoing colonoscopy.