Castor Oil is a fixed oil obtained from the seeds of the Castor Oil plant (Ricinus communis). It is regarded as one of the most valuable laxatives in medicine. It is of special service in temporary constipation and wherever a mild action is essential, and is extremely useful for children and the aged. It is a remedy for constipation. It has been used as stimulant laxative. Stimulant laxatives are used to treat constipation or before rectal or bowel examinations or surgery. They work by increasing the movement in your bowel. They also are used to treat certain conditions of the intestinal tract.
Taken internally, Castor Oil is also used as a treatment for intestinal inflammation and worms. In Asian medicine, Castor Oil is used as a remedy for joint pain, dry stool, indigestion, facial paralysis, boils, and ulcers. Homeopathic practitioners prescribe it for digestive ailments. Castor Oil has been used as a laxative since antiquity. It's mentioned by the ancient Greek historian Herodotus, and beans from the Castor plant have been found in Egyptian tombs. It's laxative effect stems from its ability to prevent absorption of liquids from the intestinal tract.
References:
PDR Health. http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/100570.shtml
Botanical.Com. http://www.botanical.com/botanical/mgmh/c/casoil32.html