Castor Oil

Also called Ricinus communis oil, ricinus oil, ricinoleic acid oil, castor oil softgels, oleum ricini.

Best grade C across 8 graded outcomes Botanical Last checked Oct 21, 2026

The short answer

From 13 sources

Castor oil is a strong stimulant laxative. Small trials suggest a single dose late in pregnancy can bring on labour, but a Cochrane review judged the evidence poor and found that everyone who drank it felt nauseous. LactMed warns against giving it to newborns. Hair-growth claims lack controlled trials; one small eyelid trial found benefit in blepharitis.

Every graded outcome on this page

8 rows · line = participants

Grade CLabour onset and cervical ripening late in pregnancyLabour inductionn 902
Grade CLabour within 48 hours at 40 to 41 weeksLabour inductionn 210
Grade CBowel cleansing before barium enemaBowel preparationn 100
Grade CEntering active labour within 48 hours, post-date pregnancyLabour inductionn 81
Grade CLabour onset within 24 hours after a previous caesareanLabour inductionn 70
Grade CBowel cleansing before colonoscopyBowel preparationn 70
Grade DEyelid inflammation (blepharitis) signs and symptomsBlepharitis (eyelids)n 26
No effectCaesarean birth and newborn outcomes after castor oil for labourLabour inductionn 233
5 more graded outcomes, in the evidence chapter

Key facts

What it is: Oil pressed from castor beans; purification removes the toxic ricin, and the oil is mostly ricinoleic acid esters¹
Main effect: A strong stimulant laxative; OTC labels say it generally produces a bowel movement in 6 to 12 hours^1,10
Labour evidence: Cochrane (3 trials, 233 women) found no difference in caesarean rates and nausea in everyone who drank castor oil; a 2022 meta-analysis of 8 studies (902 women) reported higher odds of labour starting^2,3
Studied dose: Single 60 ml doses in the labour and bowel-preparation trials that report the amount^4,5,7
Infants: LactMed: giving castor oil to newborns is dangerous and should be avoided¹
Topical use: One 4-week trial in 26 people found eyelid castor oil eased blepharitis; a 2022 review found only weak evidence for hair luster and none strong for hair growth^11,13

What it is

Castor oil is pressed from the seeds of Ricinus communis; purification removes the toxin ricin, and its main fatty acid is ricinoleic acid.

How it works

Proposed

Castor oil acts as a strong stimulant laxative through its ricinoleic acid, little of which is thought to be absorbed from the intestine. Its proposed role in starting labour is poorly understood.^1,2

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Castor Oil forms compared

2 forms

Castor Oil forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 forms	Oral castor oil (liquid)	Topical castor oil (skin, hair, castor oil packs)
Absorption in people	LactMed: little of the active ricinoleic acid is thought to be absorbed from the intestine.¹	No human absorption data in our sources.⁹
GI tolerance	Nausea in everyone who drank it in the Cochrane labour trials; more abdominal pain and nausea than magnesium citrate with bisacodyl before colonoscopy.^2,7	No adverse events in a 4-week trial of twice-daily eyelid application in 26 people.¹¹
Studied for	Labour onset late in pregnancy; bowel preparation before imaging; occasional constipation (OTC laxative label: 15 to 60 ml once daily for adults).	Blepharitis (one small 4-week eyelid trial); no controlled trial of hair growth in our sources.

Oral castor oil (liquid)
Absorption in people
LactMed: little of the active ricinoleic acid is thought to be absorbed from the intestine.¹
GI tolerance
Nausea in everyone who drank it in the Cochrane labour trials; more abdominal pain and nausea than magnesium citrate with bisacodyl before colonoscopy.^2,7
Studied for
Labour onset late in pregnancy; bowel preparation before imaging; occasional constipation (OTC laxative label: 15 to 60 ml once daily for adults).
Topical castor oil (skin, hair, castor oil packs)
Absorption in people
No human absorption data in our sources.⁹
GI tolerance
No adverse events in a 4-week trial of twice-daily eyelid application in 26 people.¹¹
Studied for
Blepharitis (one small 4-week eyelid trial); no controlled trial of hair growth in our sources.

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

8 graded outcomes, largest study first

8 graded outcomes: 3 improved, 2 mixed, 2 no effect, 1 worsened. The largest, a 2022 meta-analysis of 902 people on labour onset and cervical ripening late in pregnancy, found mixed results. One outcome found a worsening: bowel cleansing before colonoscopy (70 people).

By sizeTable

1Labour onset and cervical ripening late in pregnancy

Mixed · Grade C · Meta-analysis, 902 people, 2022

Pregnant women at or past term in 8 studies

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Labour onset and cervical ripening late in pregnancy	Mixed	902	Grade C · Meta-analysis, 2022	Pregnant women at or past term in 8 studies
Caesarean birth and newborn outcomes after castor oil for labour	No effect	233	No-effect grade · Meta-analysis, 2013	Women in the third trimester in 3 trials
Labour within 48 hours at 40 to 41 weeks	Improved	210	Grade C · RCT, 2026	Women at 40+0 to 41+0 weeks in two Enugu hospitals (Nigeria); 70 per arm
Bowel cleansing before barium enema	No effect	100	Grade C · RCT, 2009	Patients referred for barium enema (Thailand)
Entering active labour within 48 hours, post-date pregnancy	Mixed	81	Grade C · RCT, 2018	Low-risk post-date singleton pregnancies, outpatient
Labour onset within 24 hours after a previous caesarean	Improved	70	Grade C · RCT, 2022	Women with one previous caesarean attempting vaginal birth (Egypt)
Bowel cleansing before colonoscopy	Worsened	70	Grade C · RCT, 1999	Outpatients scheduled for colonoscopy (Taiwan)
Eyelid inflammation (blepharitis) signs and symptoms	Improved	26	Grade D · RCT, 2021	Adults with blepharitis; one eye treated, the other eye as control

Every graded row

8 rows

Form tested

Showing 8 of 8 outcomes. Human trials only.

Grade CLabour onset and cervical ripening late in pregnancyLabour inductionOdds of labour onset 11.67Meta-analysis · 8 studies
n 902 · 2022

Mixed Labour induction odds ratio 11.67 (95% CI 3.34 to 40.81) and higher Bishop scores (SMD 1.64) versus control; the reported Bishop-score confidence interval (1.67 to 2.11) does not contain its own point estimate.

Design: Meta-analysis, 8 studies, n = 902, 2022
Population: Pregnant women at or past term in 8 studies
Form: Oral castor oil, single dose
Dose: Single oral dose (amounts varied by study)
Duration: Single dose
Source: Reference 3 · PubMed 35837141 (opens PubMed)

Grade CLabour within 48 hours at 40 to 41 weeksLabour induction52.9% vs 24.3% in labour by 48 hRCT
n 210 · 2026

Improved Labour within 48 hours in 52.9% with castor oil vs 24.3% with expectant care (OR 3.50); membrane sweeping 62.9%, not significantly different from castor oil.

Design: RCT, n = 210, 2026
Population: Women at 40+0 to 41+0 weeks in two Enugu hospitals (Nigeria); 70 per arm
Form: Castor oil vs membrane sweeping vs expectant care
Dose: Single dose (amount not stated in the abstract)
Duration: Single dose
Source: Reference 6 · PubMed 42671437 (opens PubMed)

Grade CBowel cleansing before barium enemaBowel preparationComparable to sodium phosphateRCT
n 100 · 2009

No effect No difference in satisfaction or colon cleanliness; sodium phosphate caused more bowel movements and cost more.

Design: RCT, n = 100, 2009
Population: Patients referred for barium enema (Thailand)
Form: Castor oil vs sodium phosphate preparation
Dose: Not stated in the abstract
Duration: Before the examination
Source: Reference 8 · PubMed 19253801 (opens PubMed)

Grade CEntering active labour within 48 hours, post-date pregnancyLabour inductionEffect in multiparous women onlyRCT
n 81 · 2018

Mixed Benefit only in women who had given birth before (hazard ratios 2.78 to 3.29 at 24 to 48 hours); no effect in first-time mothers and no difference in complications.

Design: RCT, n = 81, 2018
Population: Low-risk post-date singleton pregnancies, outpatient
Form: Castor oil vs sunflower oil placebo
Dose: 60 ml once
Duration: Single dose
Source: Reference 4 · PubMed 28750937 (opens PubMed)

Grade CLabour onset within 24 hours after a previous caesareanLabour inductionLabour in 24 h: 45.7% vs 8.5%RCT
n 70 · 2022

Improved Labour started within 24 hours in 45.7% with castor oil vs 8.5% with placebo; successful vaginal birth 65.7% vs 48.5%.

Design: RCT, n = 70, 2022
Population: Women with one previous caesarean attempting vaginal birth (Egypt)
Form: Castor oil vs sunflower oil
Dose: 60 ml once
Duration: Single dose
Source: Reference 5 · PubMed 34886746 (opens PubMed)

Grade CBowel cleansing before colonoscopyBowel preparationWorse right-colon cleansing, more pain and nauseaRCT
n 70 · 1999

Worsened Castor oil cleaned the ascending colon and caecum less well (score 3.5 vs 5.2) and caused more abdominal pain (38% vs 11%) and nausea (29% vs 8%).

Design: RCT, n = 70, 1999
Population: Outpatients scheduled for colonoscopy (Taiwan)
Form: Castor oil vs magnesium citrate plus bisacodyl
Dose: 60 ml castor oil once
Duration: Day before the examination
Source: Reference 7 · PubMed 10634161 (opens PubMed)

Grade DEyelid inflammation (blepharitis) signs and symptomsBlepharitis (eyelids)Better eyelid signs and symptomsRCT
n 26 · 2021

Improved Symptom scores (OSDI) fell, and eyelid-margin thickening, eyelash matting, eyelash loss and dandruff-like crusting improved in treated eyes only; no adverse events were reported.

Design: RCT, n = 26, 2021
Population: Adults with blepharitis; one eye treated, the other eye as control
Form: Topical 100% cold-pressed castor oil on the eyelids
Dose: Applied twice daily
Duration: 4 weeks
Source: Reference 11 · PubMed 32422285 (opens PubMed)

No effectCaesarean birth and newborn outcomes after castor oil for labourLabour inductionCaesarean RR 2.04 (not significant)Meta-analysis · 3 studies
n 233 · 2013

No effect No difference in caesarean section (RR 2.04, 95% CI 0.92 to 4.55), instrumental delivery, meconium-stained liquor or low Apgar score; all women who drank castor oil felt nauseous (RR 59.92).

Design: Meta-analysis, 3 studies, n = 233, 2013
Population: Women in the third trimester in 3 trials
Form: Oral castor oil, single dose
Dose: Single dose
Duration: Single dose
Source: Reference 2 · PubMed 23881775 (opens PubMed)

Castor oil and gut permeability (human pilot study)

1 note

A provocation test in healthy volunteers, not a benefit outcome, so it is not graded.

Leakier gut at 3,000 mg: In a 2025 randomized, placebo-controlled pilot study, healthy adults took 750, 1,500 or 3,000 mg of castor oil a day. At 3,000 mg, urine tests showed higher small-intestine and colon permeability than placebo; researchers proposed it as a test model for disrupting the gut barrier. Funded by Pfizer, which employed four authors.¹²

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

Two reviews, two answers

The 2013 Cochrane review saw no clear benefit and universal nausea in 3 poor-quality trials; a 2022 meta-analysis of 8 studies reported much higher odds of labour but contains a reporting inconsistency, so neither settles the question.^2,3

Not the best bowel prep

Before colonoscopy, castor oil cleaned the right colon less well and caused more pain and nausea than magnesium citrate with bisacodyl.⁷

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from single unstated doses in the meta-analysed labour studies to a single 60 ml dose (labour onset, bowel preparation); no trial studied regular daily use.^3,4,5,7

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

What Castor Oil meets

1 cited row

Medicines 1

Castor Oil1 medicine · 0 supplements

Supplements and foods 0

No supplement rows in our sources.

Drug label or FDA notice

Interactions

1 agent

Published interactions, grouped by kind
Agent	What the source says	Evidence
Medicines1
Other oral medicinese.g. Any drug taken by mouth	The OTC laxative label says laxatives may affect how other drugs work: take castor oil 2 or more hours before or after other drugs, and ask a doctor or pharmacist first if you take any other drug.¹⁰	Drug label

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Castor Oil and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Castor Oil.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

6 groups

Pregnancy: The labour trials gave castor oil at or past term within study care; Cochrane judged the evidence poor and reported nausea in everyone who drank it. NCCIH notes many supplements are untested in pregnancy. The OTC laxative label says to ask a health professional before use if pregnant or breastfeeding.^2,9,10
Breastfeeding: LactMed: no data exist on castor oil in breast milk; because of the lack of information, other laxatives may be preferred by nursing mothers.¹
Newborns, infants and children: LactMed: giving castor oil to newborns is dangerous and should be avoided; the practice has often caused adverse effects. The OTC label says not to use it in children under 2 (consult a doctor); for children 2 to under 12 it directs 5 to 15 ml once daily.^1,10
Regular or long use, and abdominal symptoms: The OTC label limits use to 1 week, says to ask a doctor first with abdominal pain, nausea or vomiting or a sudden bowel-habit change lasting 2 weeks, and to stop and seek advice with rectal bleeding or no bowel movement after use.¹⁰
Castor beans: The beans contain the toxin ricin; only purified oil has had the ricin removed.¹
People on medicines: The OTC label advises separating castor oil from other medicines by 2 or more hours, and NCCIH advises telling your health care providers about any supplement you use.^10,9

How to read the label

What to check on the Supplement Facts panel.

How to read the label

3 checks

Oral or external use

Check whether the product is labelled for oral use; the labour and bowel trials used oral castor oil, while the only topical trial in our sources applied 100% cold-pressed oil to the eyelids.^3,4,11,10

Galactagogue claims

LactMed: no scientifically valid trials support castor oil for increasing or reducing milk supply.¹

OTC laxative directions

US castor oil sold as a stimulant laxative is labelled for adults and children over 12 at 15 to 60 ml in a single daily dose, for no longer than 1 week; it generally works in 6 to 12 hours.¹⁰

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

6 answers

Does castor oil induce labour?

Possibly, but the evidence is weak. Small trials report more women starting labour within 24 to 48 hours after a single 60 ml dose, while a Cochrane review of 3 poor-quality trials found no difference in caesarean rates and nausea in every woman who drank it. These trials ran under obstetric supervision.^2,4,5,6

Does castor oil grow hair or eyelashes?

There is no controlled trial of hair or eyelash growth in our sources. A 2022 systematic review found weak evidence that castor oil improves hair luster and no strong evidence for hair growth. In a small blepharitis trial, eyelash loss improved in the eyes that received castor oil, but that trial did not test growth in healthy lashes.^13,11

Can castor oil be used every day?

No trial in our sources tested regular daily use. The OTC laxative label says not to use it for longer than 1 week, and to ask a doctor if there is abdominal pain, nausea or vomiting, or a sudden bowel-habit change lasting 2 weeks.¹⁰

Are castor beans poisonous?

Yes. LactMed notes the beans contain small amounts of the toxin ricin; pressing the beans gives the oil, and purifying it removes the ricin.¹

What are the side effects?

Nausea was universal in the Cochrane labour trials, and abdominal pain and nausea were more common than with magnesium citrate and bisacodyl before colonoscopy.^2,7

Is castor oil a laxative, and how fast does it work?

Yes. LactMed describes it as a strong stimulant laxative, and OTC labels say it generally produces a bowel movement in 6 to 12 hours, at 15 to 60 ml once daily for adults.^1,10

Sources

13 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

13 sources

1Castor.Database Drugs and Lactation Database (LactMed), NICHD, 2024 · PMID 30000935
2Castor oil, bath and/or enema for cervical priming and induction of labour.Meta-analysis Cochrane Database Syst Rev, 2013 · PMID 23881775
3Effect of Castor Oil on Cervical Ripening and Labor Induction: a systematic review and meta-analysis.Meta-analysis J Pharmacopuncture, 2022 · PMID 35837141
4Castor oil for induction of labor in post-date pregnancies: A randomized controlled trial.RCT Women Birth, 2018 · PMID 28750937
5Castor oil for labor initiation in women with a previous cesarean section: a double-blind randomized study.RCT J Matern Fetal Neonatal Med, 2022 · PMID 34886746
6Effectiveness of Membrane Stripping Versus Castor Oil for Induction of Labor in Prevention of Post-Term Pregnancy in Enugu: A Randomized Controlled Trial.RCT Niger J Clin Pract, 2026 · PMID 42671437
7Magnesium citrate-bisacodyl regimen proves better than castor oil for colonoscopic preparation.RCT J Gastroenterol Hepatol, 1999 · PMID 10634161
8Prospective, randomized comparison of castor oil and sodium phosphate preparation for barium enema.RCT J Med Assoc Thai, 2009 · PMID 19253801
9Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
10CVS Castor Oil (castor oil USP 100%), stimulant laxative: Drug Facts labelLabel DailyMed (U.S. National Library of Medicine), 2026 · dailymed.nlm.nih.gov
11Randomized trial of topical periocular castor oil treatment for blepharitis.RCT Ocul Surf, 2021 · PMID 32422285
12Effects of Ricinoleic Acid (Castor Oil) on Gut Permeability in Healthy Participants: Provocative Test for Treatments Aimed at Restoring Barrier Function.RCT Clin Transl Gastroenterol, 2025 · PMID 40434309
13Coconut, Castor, and Argan Oil for Hair in Skin of Color Patients: A Systematic Review.Systematic review J Drugs Dermatol, 2022 · PMID 35816075

What changed

Every dated change to this page: what changed, who made it and why.

Change log

2 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026summary, key facts, evidence, research notes, forms, interactions, who should avoid, label guide, FAQ, questions, related	Added a graded row for eyelid castor oil in blepharitis (2021 RCT, 26 people, D), a research note on a 2025 Pfizer-funded pilot study showing higher gut permeability at 3,000 mg/day, and a 2022 systematic review on hair oils (FAQ, key facts). Added the US OTC castor oil Drug Facts label (DailyMed): the interaction with other oral medicines (take 2 hours apart), the 1-week limit, children's dosing and warnings, and how fast it works. Replaced the breastfeeding FAQ (already answered by the page's own pregnancy and breastfeeding question and safety notes) with one on castor beans. Re-read the LactMed Castor entry (revised 2024; no changes needed). LiverTox has no castor oil entry. PubMed search for labour-induction meta-analyses and trials 2023–2026 found nothing newer than the rows already listed.	Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md
Oct 15, 2026all	Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal; none retracted; the LactMed entry carries its 2024 update year) and each cited abstract read; numbers taken from the abstracts, with the 2022 meta-analysis sample size (902) and funder taken from its full text. Funding disclosed: Mashhad University of Medical Sciences (2022 meta-analysis); no conflicts known (Cochrane); not stated in the other abstracts. Safety from LactMed and NCCIH's Using Dietary Supplements Wisely. Where to buy: we didn’t list a product, because of the safety concerns on this page; the oral castor oil softgels we checked also contain fennel oil, and the liquid castor oils are labelled for external use only (checked 2026-10-15).	Writer: Kymata Health EditorialTrigger: new page

Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.

Castor Oil

Medicines 1

Supplements and foods 0

Other oral medicines