Castor Oil (Monograph)

Brand names: Emulsoil, Neoloid, Purge
Drug class: Cathartics and Laxatives
ATC class: A06AB05
VA class: GA204
CAS number: 8001-79-4

Medically reviewed by Drugs.com on Oct 2, 2023. Written by ASHP.

Introduction

Castor oil, a stimulant laxative, is a fixed oil obtained from the seeds of Ricinus communis.

Uses for Castor Oil

Constipation

Has been used as a stimulant laxative to relieve occasional constipation. However, castor oil usually is avoided for simple constipation because it produces violent purgation.

Use of stimulant laxatives for simple constipation is seldom necessary or desirable.

If a stimulant laxative is used, senna derivatives are preferred.

Stimulant laxatives have been used to treat constipation that occurs following prolonged bed rest or hospitalization.

Stimulant laxatives have been used to treat constipation resulting from diminished colonic motor response in geriatric patients but, because this type of constipation is frequently due to psychological or physical laxative dependence, the bulk-forming laxatives are preferred.

Stimulant laxatives are used to treat constipation occurring secondary to idiopathic slowing of transit time, to constipating drugs, or to irritable bowel or spastic colon syndrome.

Stimulant laxatives have been used to treat constipation in patients with neurologic constipation.

Colonic Evacuation

Used orally to empty the bowel prior to surgery or radiologic, proctoscopic, or sigmoidoscopic procedures, when thorough evacuation is essential.

Usually supplemented with administration of rectal evacuants, such as saline, stimulant, or soapsuds enemas, immediately before radiologic procedures.

Castor Oil Dosage and Administration

Administration

Oral Administration

Administer orally.

Emulsions or aromatic or flavored preparations somewhat mask the disagreeable taste of castor oil.

Containers of the emulsion should be shaken before using, and the emulsion may be mixed with 120–240 mL of water, milk, fruit juice, or soft drink before administration.

Dosage

Usually reserved for total colonic evacuation, such as prior to surgery or radiologic, sigmoidoscopic, or proctoscopic procedures.

Pediatric Patients

Constipation

Use in children for occasional constipation generally is avoided.

Colonic Evacuation

To prepare for colonic surgery or radiologic, sigmoidoscopic, or proctoscopic procedures, the patient should receive a residue-free diet 1 day before the surgery or procedure and a cleansing rectal enema (e.g., tap water, soap suds, saline laxative, bisacodyl) on the day of the examination.

Additionally, standardized senna fruit extract may be administered 4 hours after castor oil.

Oral

Administer as a single dose about 16 hours before surgery or procedure.

Children <2 Years of Age: 1–5 mL.

Children 2–11 Years of Age: 5–15 mL for children.

Children ≥12 years of Age: Usually, 15–60 mL.

Adults

Constipation

Oral

15 mL, but rarely indicated for occasional constipation.

Colonic Evacuation

To prepare for colonic surgery or radiologic, sigmoidoscopic, or proctoscopic procedures, the patient should receive a residue-free diet 1 day before the surgery or procedure and a cleansing rectal enema (e.g., tap water, soap suds, saline laxative, bisacodyl) on the day of the examination.

Additionally, standardized senna fruit extract may be administered 4 hours after castor oil.

Oral

Administer as a single dose about 16 hours before the surgery or procedure.

15–60 mL.

Special Populations

Hepatic Impairment

No specific dosage recommendations for hepatic impairment.

Renal Impairment

No specific dosage recommendations for renal impairment.

Geriatric Patients

No specific geriatric dosage recommendations.

Cautions for Castor Oil

Contraindications

• In acute abdominal pain, nausea, vomiting, or other symptoms of appendicitis or undiagnosed abdominal pain or rectal bleeding.

• Intestinal obstruction.

• Pregnancy or menstruation.

Warnings/Precautions

Warnings

Chronic Use or Overdosage

Chronic use or overdosage may produce persistent diarrhea, hypokalemia, loss of essential nutritional factors, and dehydration.

Factitious diarrhea (i.e., severe, chronic, watery diarrhea, frequently occurring at night and accompanied by abdominal pain, weight loss, nausea, and vomiting).

Electrolyte disturbances including hypokalemia, hypocalcemia, metabolic acidosis or alkalosis, abdominal pain, diarrhea, malabsorption, weight loss, and protein-losing enteropathy may occur. May require immediate medical intervention with appropriate fluid and electrolyte replacement.

Electrolyte disturbances may produce vomiting and muscle weakness; rarely, osteomalacia, secondary aldosteronism, and tetany may occur.

Pathologic changes including structural damage to the myenteric plexus, severe and permanent interference with colonic motility, and hypertrophy of the muscularis mucosae may occur with chronic use.

Protein-losing enteropathy and steatorrhea can occur.

“Cathartic colon” with atony and dilation of the colon, especially of the right side, has occurred with habitual use (often for several years) and often resembles ulcerative colitis.

Specific Populations

Pregnancy

Category X.

Lactation

Not known whether castor oil or ricinoleic acid is distributed into milk.

Pediatric Use

Stimulant laxatives generally avoided in children younger than 6–10 years of age for occasional constipation.

Used in all age groups for colonic evacuation.

Common Adverse Effects

Abdominal discomfort, nausea, cramps, griping, and/or faintness.

Even at therapeutic doses, excessive irritation of the colon and violent purgation.

Diarrhea, GI irritation, and fluid and electrolyte depletion.

May rarely cause pelvic congestion.

Drug Interactions

GI Drug Absorption

By increasing intestinal motility, can potentially decrease transit time of concomitantly administered oral drugs and thereby decrease their absorption.

Castor Oil Pharmacokinetics

Absorption

Bioavailability

Extent of GI absorption of castor oil is unknown.

Ricinoleic acid, the active metabolite, is absorbed to a small extent.

Onset

Loose bowel movements usually occur within 2–3 hours (range: 2–6 hours) following orall administration.

Food

Most effective when administered on an empty stomach.

Elimination

Metabolism

In the small intestine, castor oil is hydrolyzed by pancreatic lipase to its active principle, ricinoleic acid.

Elimination Route

Systemically absorbed ricinoleic acid is metabolized like other fatty acids.

Stability

Storage

Oral

To avoid rancidity, do not expose to temperatures >40°C.

Tight containers; avoid exposure to excessive heat.

Emulsions also should be protected from freezing.

Actions

• Castor oil, a stimulant laxative, is a fixed oil obtained from the seeds of Ricinus communis Linné.

• Aromatic castor oil is a solution of castor oil in alcohol containing suitable flavoring agents. Aromatic castor oil contains not less than 95% castor oil and not more than 4% alcohol.

• Ricinoleic acid, which is produced by hydrolysis via pancreatic lipase in the small intestine, is responsible for castor oil’s laxative action.

• Precise mechanism unknown.

• Commonly thought that stimulant laxatives induce defecation by stimulating propulsive peristaltic activity of the intestine through local irritation of the mucosa or through a more selective action on the intramural nerve plexus of intestinal smooth muscle, thus increasing motility.

• More recent evidence shows that stimulant laxatives alter fluid and electrolyte absorption, producing net intestinal fluid accumulation and laxation.

• Stimulant laxatives mainly promote evacuation of the colon; however, castor oil also directly or reflexly increases activity of the small intestine.

• Castor oil produces violent purgation in therapeutic doses.

Advice to Patients

• Importance of not taking castor oil at bedtime since the laxative effect occurs quickly.

• Advise patients that prolonged use can cause excessive loss of fluids, electrolytes, and nutrients.

• Importance of not using laxative products for a period longer than 1 week unless directed by a clinician.

• Importance of informing clinicians before use if abdominal pain, nausea, or vomiting is present or if a sudden change in bowel habits that persists over a period of 2 weeks has been noticed.

• Advise about risk of laxative abuse and potential serious consequences. (See Chronic Use or Overdosage under Cautions.)

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs as well as any concomitant illnesses.

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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