Castor oil is the 1 home remedy for starting labour with 3 randomised trials behind it. That fact is exactly why it needs careful handling rather than enthusiasm.
Three trials covering 233 women sit in a Cochrane review, and the most consistent finding in them is not effectiveness. It is that essentially 100% of women felt nauseous.
Quick Answer: Does Castor Oil Induce Labor?
It has been studied, which puts it ahead of most home methods, but the evidence is thin and the side effects are not. A Cochrane review of 3 trials in 233 women found no difference in caesarean rate, no mortality data at all, and near-universal nausea. This belongs with a midwife or obstetrician, never as a DIY plan.
Key Takeaways
- A Cochrane review covers 3 trials and 233 women in total.
- Caesarean rates showed no difference, with a risk ratio of 2.04.
- Not 1 of the 3 studies reported maternal or neonatal mortality.
- Essentially 100% of the women who drank it reported nausea.
- A later trial randomised 81 women to 60 mL against sunflower oil.
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What the Cochrane Review Found
This is the closest thing to a definitive answer, and it is more cautious than any blog post. The review pooled every trial it could find on castor oil for cervical priming and induction.
| Outcome | Finding |
|---|---|
| Trials and participants | 3 trials, 233 women |
| Caesarean section rate | No evidence of difference, RR 2.04, CI 0.92 to 4.55 |
| Maternal or neonatal mortality | Not reported in any study |
| Instrumental delivery | No evidence of difference |
| Meconium-stained liquor | No evidence of difference |
| Nausea | Essentially universal, RR 59.92 |
For context on what this oil is and what else it is sold for, see what castor oil actually is.
The authors were explicit that the numbers are small and the results should be read with caution because of the risk of bias.[1]Castor oil, bath and/or enema for cervical priming and induction of labour — Cochrane Database of Systematic Reviews (2013) View source A wide confidence interval like 0.92 to 4.55 means the honest reading is that nobody knows.
The Nausea Finding Deserves Its Own Line
Most reviews report side effects as a footnote. Here the side effect is the most statistically solid thing in the entire dataset, and it is worth stating plainly.
- How common: All women who ingested castor oil felt nauseous.
- The statistic: A risk ratio of 59.92 against comparison.
- Why it matters: Vomiting in late pregnancy is not trivial.
- Context: This is a cathartic, so the effect is expected.
A method whose most reliable outcome is vomiting is not a method to run alone at home. The same cathartic action is what makes it work as a laxative in non-pregnant adults.[3]An examination of the effect of castor oil packs on constipation in the elderly — Complementary Therapies in Clinical Practice (2011) View source
The Later Randomised Trial
A more recent study tested the outpatient version of the question, which is closer to what people actually ask about. Its design is worth knowing even before the results.
| Design element | Detail |
|---|---|
| Participants | 81 women, low-risk post-date singleton pregnancy |
| Cervix | Bishop score of 7 or under, no effective contractions |
| Intervention | 60 mL of castor oil |
| Control | 60 mL of sunflower oil |
| Primary outcome | Active labour at 24, 36 and 48 hours |
| Also tracked | Meconium staining |
Note the population: low-risk, post-date, and screened by clinicians before anything was given.[2]Castor oil for induction of labor in post-date pregnancies: A randomized controlled trial — Women and Birth (2018) View source None of that describes someone deciding at 38 weeks to try it because of a forum post.
Why This Is Not a DIY Method
The gap between the trial setting and home use is the whole safety story. Four differences matter more than the efficacy question.
- Screening: Trial participants were assessed as low-risk first.
- Timing: Post-date, not merely uncomfortable at 38 weeks.
- Monitoring: Someone was watching for meconium and distress.
- Backup: A hospital was available if labour went badly.
If you are past your due date and considering this, the conversation belongs with your midwife or obstetrician, not with a bottle. The castor oil we sell is labelled for topical and laxative use only.
What About Packs During Pregnancy
The same logic covers abdominal use. Given that the oil is studied as a labour agent, putting it on a pregnant abdomen is not a neutral act even if absorption is minimal.
- Default: Avoid abdominal packs while pregnant.
- Reason: The same substance is trialled to start labour.
- Evidence: 0 trials have tested packs in pregnancy.
- Alternative: Ask your midwife what is appropriate.
The pack evidence in non-pregnant adults is set out in what the only pack trial found.
Speak to a Midwife or Obstetrician Before Anything If
- Abdominal pain with vomiting, which needs assessment rather than a laxative
- Blood in the stool, or black stools
- Constipation that is new after age 50
- Unexplained weight loss alongside a change in bowel habit
- Any use to start labour without a midwife or obstetrician
- Eye pain or a change in vision after a home application
Frequently Asked Questions
Does castor oil actually start labor? +
The evidence is 3 small trials in 233 women, and it does not establish that. What it does show clearly is that essentially every woman who took it felt nauseous.
How much castor oil was used in the trials? +
The later randomised trial used 60 mL against 60 mL of sunflower oil as a control. The Cochrane trials all used single doses rather than repeated ones.
Is it safe to try at home? +
No, and that is the main message of this page. Trial participants passed 3 filters: screened as low-risk, genuinely post-date, and monitored with a hospital behind them.
Does castor oil cause meconium in the baby? +
The Cochrane review found no evidence of a difference in meconium-stained liquor across the 3 trials. That is reassurance from small numbers rather than a guarantee.
Why does it make you feel so sick? +
It is a cathartic, so it irritates the gut deliberately. The risk ratio for nausea in the review was 59.92, which is 1 of the largest effects in the whole dataset.
How long after taking it would labor start? +
The later trial measured active labour at 24, 36 and 48 hours. There is no reliable window, which is another reason it is not a home method.
Can I use a castor oil pack instead while pregnant? +
Avoid it. There are 0 trials of packs in pregnancy, and the same oil is being studied as a labour agent, so a pregnant abdomen is not the place to experiment.
Does it increase the chance of a caesarean? +
The pooled risk ratio was 2.04 with a confidence interval of 0.92 to 4.55, which crosses 1. That means the data cannot tell you either way.
What do midwives think of it? +
It has been used in midwifery practice traditionally, which is why the trials exist at all. That history is exactly why it should be discussed with 1 rather than used behind their back.
Are there safer ways to encourage labor? +
Membrane sweeping and formal induction are clinician-led options with far better data. Both belong to a conversation at your 40-week appointment rather than a kitchen cupboard.
What if I already took it? +
Expect nausea and urgent bowel movements, keep fluids up, and tell your midwife or maternity unit. Any of these 3 need immediate contact: bleeding, reduced fetal movements, or contractions.
Related Reading
- How the Laxative Effect Works
- Documented Harms and Cautions
- Topical Use on Face and Skin
- What Castor Oil Does to Hair
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