Mustard oil is extracted from Brassica nigra (also known as Sinapsis nigra and Brassica sinapioides) of the Cruciferae family. Mustard oil is a hazardous oil because of its high content of allyl isothiocyanate. The powder or seed does not contain allyl isothiocyanate as this is only formed during the production of the essential oil. In herbal medicine, the seeds are used to aid digestion, to promote the appetite, and for colds, chills, coughs, chilblains, rheumatism, arthritis, lumbago, and aches and pains. As an essential oil, mustard oil is toxic because of its high content of allyl isothiocyanate. The oil is a skin and mucus membrane irritant. When mustard oil is inhaled, it produces an extremely unpleasant sensation in the occipital regions of the head and causes inflammation of the conjunctiva of the eyes and the mucus membranes of the respiratory system. When applied to the skin, it provokes a burning sensation and should never be used in aromatherapy.
