Castor oil is derived from seeds of the plant Ricinus communis. These seeds, commonly called beans, are poisonous, but castor oil labeled as edible or for internal use is safe to consume in small amounts, as long as you buy from reputable manufacturers. Edible castor oil can be used for constipation, although it's best not to do so on a regular basis. Consult a qualified health care provider before taking castor oil for constipation or any other health problem.
Stimulant laxatives such as castor oil are effective for treating constipation, but they are harsher than other methods of relieving this problem, such as fiber supplements or stool softeners. Castor oil works by causing contractions in your bowel, which pushes the stool out. If you take castor oil or other stimulant laxatives regularly or on a long-term basis, your bowel can lose muscle tone, which can lead to chronic constipation, according to the American Academy of Family Physicians at FamilyDoctor.org.
If you're interested in taking edible castor oil for constipation, use no more than the dose specified on the label. Take the oil on an empty stomach with an 8-oz. glass of water. Because castor oil has an unpleasant taste, you might want to mix it with cold orange juice, recommends MedlinePlus. Although most stimulant laxatives are taken at bedtime to produce a stool during the next day, castor oil acts relatively fast, so take it when you're going to be awake and able to get to a bathroom quickly.
Don't take castor oil or any other stimulant laxative for longer than a week without your doctor's instructions to do so, advises MedlinePlus. In addition, don't take more than the recommended dose because that can lead to serious side effects. If you don't pass a stool after consuming castor oil, call your doctor rather than ingesting more oil. Don't give castor oil to a child younger than 10 years old without your doctor's direction.
Castor oil may cause side effects such as diarrhea, abdominal cramps, nausea, vomiting and urine discoloration, particularly if you take more than recommended. Call your doctor if these effects become severe. Adverse reactions such as dizziness, fainting, shortness of breath, chest pain, throat tightness, a rash, bloody stools, rectal bleeding or general weakness call for immediate medical attention.