Bitter orange oil is made from the peel. In manufacturing, bitter orange oil is used in pharmaceuticals, cosmetics, and soaps. In aromatherapy, the essential oil of bitter orange is applied to the skin and also inhaled as a painkiller. Bitter orange peel is applied to the skin for swelling (inflammation) of the eyelid and its lining, as well as the retina in the eye. It is also used for bleeding from the retina, exhaustion accompanying colds, headaches, nerve pain, muscular pain, joint pain, bruises, swelling of the veins (phlebitis), and bed sores.