Castor oil is a multipurpose vegetable oil that people have used for thousands of years. It’s made by extracting oil from the seeds of the Ricinus communis plant. These seeds, which are known as castor beans, contain a toxic enzyme called ricin. However, the heating process that castor oil undergoes during production deactivates the ricin, allowing the oil to be used safely. Castor oil has a number of medicinal, industrial, and pharmaceutical uses.