Peanut oil is the oil from the seed, also called the nut, of the peanut plant. Peanut oil is used to make medicine. It is used to lower cholesterol and prevent heart disease because it is high in monounsaturated (good) fat, and low in saturated (bad) fat. It is also used to decrease appetite as an aid to weight loss. Some people use it to help prevent cancer. Peanut oil is sometimes applied directly to the skin for arthritis and joint pain, dry skin, eczema, scalp crusting and scaling without hair loss, and other skin disorders that cause scaling. Rectally, peanut oil is used in ointments and medicinal oils for treating constipation. Pharmaceutical companies use it in various products they prepare for internal and external use.