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Peppermint Oil

Also known as Mentha piperita oil, Enteric-coated peppermint oil

Oil from peppermint leaves (Mentha x piperita) whose menthol relaxes the smooth muscle of the gut. The evidence is for enteric-coated capsules in irritable bowel syndrome (IBS): the coating lets the oil pass the stomach and release in the intestine. Meta-analyses of up to 12 trials found more people improved on peppermint oil than placebo, roughly one extra responder for every 3 to 7 treated, but two recent large trials (2020 and 2021) found no significant benefit over placebo, and a 2022 review rated the evidence very low quality. Heartburn is the most common side effect.

Before you take peppermint oil

The IBS evidence is for enteric-coated capsules, which release the oil past the stomach. Swallow them whole; peppermint tea and uncoated oil are not what the trials tested.
Heartburn is the most common side effect. Avoid it if you have reflux or a hiatus hernia.
Product leaflets advise against taking indigestion remedies (antacids) at the same time, as they can dissolve the coating early.

General information, not medical advice.

What trials found, in numbers

Summaries of published trial results for this compound, grouped by condition. In these tables every number is exactly as the researchers published it. The headline figures above show a simple average where several studies measured the same thing in the same unit, and say so; nothing else is calculated or converted.

How to read this table

Benefit: What the trial saw happen: whether the measured outcome moved in the helpful direction in that one study (the tag on each row: “Benefit seen”, “No clear benefit”, “Possible harm” or “Unclear”). It is a study result — not advice, and not a promise it will work for you.
Evidence: How strong the research behind that result is. A meta-analysis pools many studies (strongest); a systematic review collates them; an RCT tests against a control (placebo); observational studies only watch — they can suggest, not prove.
Effect size: How large the measured change was, exactly as the researchers published it. “No number reported” means the abstract gave no effect size — we never invent one.

In short: benefit is what was observed; evidence is how much you should trust the observation. A “Benefit seen” tag on a weak study counts for far less than the same tag on a meta-analysis.

Digestive Health (30 outcomes)

Outcome measured	What trials found	Effect size	People studied	Duration	Type of evidence	Study
Abdominal pain (relative risk of pain not improving)	Peppermint oil improved Abdominal pain (relative risk of pain not improving) (0.76; 95% CI 0.62-0.93; 7; 95% CI 4-24) compared with placebo in 1030. (95% CI 0.62-0.93; 95% CI 4-24)Benefit seen	0.76	1030	—	Meta-analysis · 2022	PMID 35942669
adverse event rates	Peppermint oil showed harm (adverse effect) on adverse event rates (1.57; 95% CI 1.04-2.37) compared with placebo in 1030. (95% CI 1.04-2.37)Possible harm	1.57	1030	—	Meta-analysis · 2022	PMID 35942669
Global IBS symptoms (relative risk of not improving)	Peppermint oil improved Global IBS symptoms (relative risk of not improving) (0.65; 95% CI 0.43-0.98; 4; 95% CI 2.5-71) compared with placebo in 1030. (95% CI 0.43-0.98; 95% CI 2.5-71)Benefit seen	0.65	1030	—	Meta-analysis · 2022	PMID 35942669
abdominal pain	Peppermint oil improved abdominal pain (1.78; 95% CI: 1.43, 2.20; p < 0.00001) compared with placebo in 835. (95% CI: 1.43, 2.20; p < 0.00001)Benefit seen	1.78	835	—	Meta-analysis · 2019	PMID 30654773
adverse effects	Peppermint oil showed an unclear effect on adverse effects (1.40; 95% CI: 0.87, 2.26; p = 0.16) compared with placebo in 835. (95% CI: 0.87, 2.26; p = 0.16)Unclear	1.40	835	—	Meta-analysis · 2019	PMID 30654773
global symptom improvement	Peppermint oil improved global symptom improvement (2.39; 95% confidence interval (CI): 1.93, 2.97; p < 0.00001) compared with placebo in 835. (95% confidence interval (CI): 1.93, 2.97; p < 0.00001)Benefit seen	2.39	835	—	Meta-analysis · 2019	PMID 30654773
adverse events	Enteric-coated peppermint oil capsules showed harm (adverse effect) on adverse events compared with placebo.Possible harm	no number reported	—	—	Meta-analysis · 2014	PMID 24100754
global improvement of IBS symptoms	Enteric-coated peppermint oil capsules improved global improvement of IBS symptoms (2.23; 1.78-2.81) compared with placebo in 392.Benefit seen	2.23	392	—	Meta-analysis · 2014	PMID 24100754
improvement in abdominal pain	Enteric-coated peppermint oil capsules improved improvement in abdominal pain (2.14; 1.64-2.79) compared with placebo in 357.Benefit seen	2.14	357	—	Meta-analysis · 2014	PMID 24100754
Persistent IBS symptoms (relative risk, 4 trials)	Peppermint oil improved Persistent IBS symptoms (relative risk, 4 trials) (0.43; 0.32 to 0.59) compared with placebo in 392.Benefit seen	0.43	392	—	Meta-analysis · 2008	PMID 19008265
IBS symptom relief (meta-analysis of 5 double-blind RCTs; flawed trials)	Peppermint oil showed an unclear effect on IBS symptom relief (meta-analysis of 5 double-blind RCTs; flawed trials) compared with placebo.Unclear	no number reported	—	—	Meta-analysis · 1998	PMID 9672344
IBS symptom severity (IBS-SSS) change over 6 weeks	Enteric-coated peppermint oil (180 mg three times daily) did not significantly improve IBS symptom severity (IBS-SSS) change over 6 weeks (d = -0.11; P = 0.97) compared with placebo (6-week). (P = 0.97)No clear benefit	d = -0.11	—	6-week	RCT · 2021	PMID 34319275
Abdominal pain response, ileocolonic-release capsules	Ileocolonic-release peppermint oil did not significantly improve Abdominal pain response, ileocolonic-release capsules (P = .385) compared with placebo in 189 (8 weeks). (P = .385)No clear benefit	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Abdominal pain response, small-intestinal-release capsules	Small-intestinal-release peppermint oil did not significantly improve Abdominal pain response, small-intestinal-release capsules (P = .170) compared with placebo in 189 (8 weeks). (P = .170)No clear benefit	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Abdominal pain, small-intestinal-release capsules	Small-intestinal-release peppermint oil improved Abdominal pain, small-intestinal-release capsules (P = .016) compared with placebo in 189 (8 weeks). (P = .016)Benefit seen	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Adverse events, ileocolonic-release capsules	Ileocolonic-release peppermint oil showed harm (adverse effect) on Adverse events, ileocolonic-release capsules (P < .005) compared with placebo in 189 (8 weeks). (P < .005)Possible harm	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Adverse events, small-intestinal-release capsules	Small-intestinal-release peppermint oil showed harm (adverse effect) on Adverse events, small-intestinal-release capsules (P < .005) compared with placebo in 189 (8 weeks). (P < .005)Possible harm	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Discomfort, small-intestinal-release capsules	Small-intestinal-release peppermint oil improved Discomfort, small-intestinal-release capsules (P = .020) compared with placebo in 189 (8 weeks). (P = .020)Benefit seen	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
IBS severity, small-intestinal-release capsules	Small-intestinal-release peppermint oil improved IBS severity, small-intestinal-release capsules (P = .020) compared with placebo in 189 (8 weeks). (P = .020)Benefit seen	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Overall relief of IBS symptoms, ileocolonic-release capsules	Ileocolonic-release peppermint oil did not significantly improve Overall relief of IBS symptoms, ileocolonic-release capsules (P = .351) compared with placebo in 189 (8 weeks). (P = .351)No clear benefit	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Overall relief of IBS symptoms, small-intestinal-release capsules	Small-intestinal-release peppermint oil did not significantly improve Overall relief of IBS symptoms, small-intestinal-release capsules (P = .317) compared with placebo in 189 (8 weeks). (P = .317)No clear benefit	no number reported	189	8 weeks	RCT · 2020	PMID 31470006
Adverse reactions	Enteric-coated, delayed-release peppermint oil (Colpermin) did not significantly improve Adverse reactions compared with placebo in 90 (8 weeks).No clear benefit	no number reported	90	8 weeks	RCT · 2010	PMID 19507027
Patients free from abdominal pain or discomfort at week 8 (14 on peppermint oil vs 6 on placebo)	Enteric-coated, delayed-release peppermint oil (Colpermin) improved Patients free from abdominal pain or discomfort at week 8 (14 on peppermint oil vs 6 on placebo) (P < 0.001) compared with placebo in 90 (8 weeks). (P < 0.001)Benefit seen	no number reported	90	8 weeks	RCT · 2010	PMID 19507027
Quality of life	Enteric-coated, delayed-release peppermint oil (Colpermin) improved Quality of life compared with placebo in 90 (8 weeks).Benefit seen	no number reported	90	8 weeks	RCT · 2010	PMID 19507027
Severity of abdominal pain	Enteric-coated, delayed-release peppermint oil (Colpermin) improved Severity of abdominal pain compared with placebo in 90 (8 weeks).Benefit seen	no number reported	90	8 weeks	RCT · 2010	PMID 19507027
alleviation of the severity of abdominal pain	Enteric-coated peppermint oil (Colpermin) improved alleviation of the severity of abdominal pain (P < 0.05) compared with placebo in 110 (1 month). (P < 0.05)Benefit seen	no number reported	110	1 month	RCT · 1997	PMID 9430014
fewer borborygmi	Enteric-coated peppermint oil (Colpermin) improved fewer borborygmi (P < 0.05) compared with placebo in 110 (1 month). (P < 0.05)Benefit seen	no number reported	110	1 month	RCT · 1997	PMID 9430014
less abdominal distension	Enteric-coated peppermint oil (Colpermin) improved less abdominal distension (P < 0.05) compared with placebo in 110 (1 month). (P < 0.05)Benefit seen	no number reported	110	1 month	RCT · 1997	PMID 9430014
less flatulence	Enteric-coated peppermint oil (Colpermin) improved less flatulence (P < 0.05) compared with placebo in 110 (1 month). (P < 0.05)Benefit seen	no number reported	110	1 month	RCT · 1997	PMID 9430014
reduced stool frequency	Enteric-coated peppermint oil (Colpermin) improved reduced stool frequency (P < 0.05) compared with placebo in 110 (1 month). (P < 0.05)Benefit seen	no number reported	110	1 month	RCT · 1997	PMID 9430014

Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.

Understand what people are taking.

Peppermint Oil

What the research actually shows

The headline results, condition by condition

Digestive Health

Why people look into Peppermint Oil — and what they report

Where to get Peppermint Oil (UK)

Where the evidence is concentrated

Suggested uses (unproven)

Where the evidence is negative

What trials found, in numbers