Supplement

Peppermint

Peppermint is an aromatic herb whose oil contains menthol, which blocks calcium channels in the gut's smooth muscle and helps it relax. Most people look at it for irritable bowel syndrome, and the evidence is strong: across seven studies, symptoms improved. Those studies were only moderate in size, about 392 people in total, and findings for related gut outcomes like gas and colon tension rest on small, limited studies.

Sources: PMID 19507027; PMID 11148527

Updated 30 September 2026
How we grade
19 studies cited

Best evidence: Grade A
Conditions studied: 13
Outcomes: 36
Graded outcomes: 1350

Evidence by condition

Strong
Moderate
Limited
Very limited

13 conditions

Irritable Bowel Syndrome (IBS)

Irritable Bowel Syndrome (IBS): outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Irritable Bowel Syndrome Symptoms Moderate Improvement	Improves (the measure goes down)	Moderate effect	7 studies	392 people
Studies that measured irritable bowel syndrome symptoms The effect of enteric-coated, delayed-release peppermint oil on irritable bowel syndromeDig Dis Sci · PMID 19507027 Enteric-coated, pH-dependent peppermint oil capsules for the treatment of irritable bowel syndrome in childrenJ Pediatr · PMID 11148527 Treating irritable bowel syndrome with peppermint oilBr Med J · PMID 389344 Enteric-coated peppermint-oil capsules in the treatment of irritable bowel syndrome: a prospective, randomized trialJ Gastroenterol · PMID 9430014 Treatment of irritable bowel syndrome with peppermint oil. A double-blind study with a placeboUgeskr Laeger · PMID 3061106 Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trialDig Liver Dis · PMID 17420159 Efficacy of Peppermint oil in diarrhea predominant IBS - a double blind randomized placebo - controlled studyMymensingh Med J · PMID 23416804
	Flatulence Small Improvement	Improves (the measure goes up)	Small effect		42 people
	Nausea Symptoms	Improves (the measure goes down)		4 studies	42 people
Studies that measured nausea symptoms Examination of the effectiveness of peppermint aromatherapy on nausea in women post C-sectionJ Holist Nurs · PMID 22034523 Peppermint oil: a treatment for postoperative nauseaJ Adv Nurs · PMID 9378876 An investigation into the use of aromatherapy in intrapartum midwifery practiceJ Altern Complement Med · PMID 10784271 Aromatherapy with peppermint, isopropyl alcohol, or placebo is equally effective in relieving postoperative nauseaJ Perianesth Nurs · PMID 14770380
	Subjective Well-Being	Improves (the measure goes up)			90 people

Pregnancy and Delivery Health

Pregnancy and Delivery Health: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Nausea Symptoms Small Improvement	Improves (the measure goes down)	Small effect	4 studies	1,157 people
Studies that measured nausea symptoms Examination of the effectiveness of peppermint aromatherapy on nausea in women post C-sectionJ Holist Nurs · PMID 22034523 Peppermint oil: a treatment for postoperative nauseaJ Adv Nurs · PMID 9378876 An investigation into the use of aromatherapy in intrapartum midwifery practiceJ Altern Complement Med · PMID 10784271 Aromatherapy with peppermint, isopropyl alcohol, or placebo is equally effective in relieving postoperative nauseaJ Perianesth Nurs · PMID 14770380
	Nipple Cracks	Improves (the measure goes up)		2 studies	72 people
Studies that measured nipple cracks A randomized trial of peppermint gel, lanolin ointment, and placebo gel to prevent nipple crack in primiparous breastfeeding womenMed Sci Monit · PMID 17767120 Effect of peppermint water on prevention of nipple cracks in lactating primiparous women: a randomized controlled trialInt Breastfeed J · PMID 17442122
	Sedation	Improves (the measure goes up)			35 people

Surgical Recovery

Nausea Symptoms: improves
Sedation: improves

Surgical Recovery: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Nausea Symptoms Small Improvement	Improves (the measure goes down)	Small effect	4 studies	86 people
Studies that measured nausea symptoms Examination of the effectiveness of peppermint aromatherapy on nausea in women post C-sectionJ Holist Nurs · PMID 22034523 Peppermint oil: a treatment for postoperative nauseaJ Adv Nurs · PMID 9378876 An investigation into the use of aromatherapy in intrapartum midwifery practiceJ Altern Complement Med · PMID 10784271 Aromatherapy with peppermint, isopropyl alcohol, or placebo is equally effective in relieving postoperative nauseaJ Perianesth Nurs · PMID 14770380
	Sedation	Improves (the measure goes up)			35 people

Tension Headache

Headaches: improves
Irritability: improves
Subjective Well-Being: improves

Tension Headache: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Headaches Moderate Improvement	Improves (the measure goes down)	Moderate effect	2 studies	73 people
Studies that measured headaches Effectiveness of Oleum menthae piperitae and paracetamol in therapy of headache of the tension typeNervenarzt · PMID 8805113 Effect of peppermint and eucalyptus oil preparations on neurophysiological and experimental algesimetric headache parametersCephalalgia · PMID 7954745
	Irritability	Improves (the measure goes down)			32 people
	Subjective Well-Being	Improves (the measure goes up)			32 people

Migraine Headache

Headaches: improves
Irritability: improves
Subjective Well-Being: improves

Migraine Headache: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Headaches Moderate Improvement	Improves (the measure goes down)	Moderate effect	2 studies	32 people
Studies that measured headaches Effectiveness of Oleum menthae piperitae and paracetamol in therapy of headache of the tension typeNervenarzt · PMID 8805113 Effect of peppermint and eucalyptus oil preparations on neurophysiological and experimental algesimetric headache parametersCephalalgia · PMID 7954745
	Irritability	Improves (the measure goes down)			32 people
	Subjective Well-Being	Improves (the measure goes up)			32 people

Cognitive Improvement

Attention: improves
Stress Signs and Symptoms: improves
Memory: improves

Cognitive Improvement: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Attention Small Improvement	Improves (the measure goes up)	Small effect		144 people
	Stress Signs and Symptoms	Improves (the measure goes down)		1 study	144 people
Studies that measured stress signs and symptoms Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylangInt J Neurosci · PMID 18041606
	Memory	Improves (the measure goes up)			144 people
	Processing Accuracy	Improves (the measure goes up)			144 people
	Processing Speed	Improves (the measure goes up)			144 people
	Subjective Well-Being	Improves (the measure goes up)			144 people
	Working Memory	Improves (the measure goes up)			144 people

Digestive Health

Colonic Tension: improves
Pain: improves

Digestive Health: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Colonic Tension Small Improvement	Improves (the measure goes up)	Small effect		65 people
	Pain	Improves (the measure goes down)		1 study	65 people
Studies that measured pain Premedication with peppermint oil capsules in colonoscopy: a double blind placebo-controlled randomized trial studyActa Gastroenterol Belg · PMID 23082707

Mood Improvement

Attention: improves
Stress Signs and Symptoms: improves
Memory: improves

Mood Improvement: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People
	Attention Small Improvement	Improves (the measure goes up)	Small effect		144 people
	Stress Signs and Symptoms	Improves (the measure goes down)		1 study	144 people
Studies that measured stress signs and symptoms Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylangInt J Neurosci · PMID 18041606
	Memory	Improves (the measure goes up)			144 people
	Processing Accuracy	Improves (the measure goes up)			144 people
	Processing Speed	Improves (the measure goes up)			144 people
	Subjective Well-Being	Improves (the measure goes up)			144 people
	Working Memory	Improves (the measure goes up)			144 people

Morning Sickness

Irritable Bowel Syndrome Symptoms: improves

Morning Sickness: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Irritable Bowel Syndrome Symptoms	Improves (the measure goes down)		7 studies	65 people
Studies that measured irritable bowel syndrome symptoms The effect of enteric-coated, delayed-release peppermint oil on irritable bowel syndromeDig Dis Sci · PMID 19507027 Enteric-coated, pH-dependent peppermint oil capsules for the treatment of irritable bowel syndrome in childrenJ Pediatr · PMID 11148527 Treating irritable bowel syndrome with peppermint oilBr Med J · PMID 389344 Enteric-coated peppermint-oil capsules in the treatment of irritable bowel syndrome: a prospective, randomized trialJ Gastroenterol · PMID 9430014 Treatment of irritable bowel syndrome with peppermint oil. A double-blind study with a placeboUgeskr Laeger · PMID 3061106 Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trialDig Liver Dis · PMID 17420159 Efficacy of Peppermint oil in diarrhea predominant IBS - a double blind randomized placebo - controlled studyMymensingh Med J · PMID 23416804

Lactation (Breast Milk Production)

Nipple Cracks: improves

Lactation (Breast Milk Production): outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Nipple Cracks	Improves (the measure goes up)		2 studies	188 people
Studies that measured nipple cracks A randomized trial of peppermint gel, lanolin ointment, and placebo gel to prevent nipple crack in primiparous breastfeeding womenMed Sci Monit · PMID 17767120 Effect of peppermint water on prevention of nipple cracks in lactating primiparous women: a randomized controlled trialInt Breastfeed J · PMID 17442122

Skin Health

Nipple Cracks: improves

Skin Health: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Nipple Cracks	Improves (the measure goes up)		2 studies	72 people
Studies that measured nipple cracks A randomized trial of peppermint gel, lanolin ointment, and placebo gel to prevent nipple crack in primiparous breastfeeding womenMed Sci Monit · PMID 17767120 Effect of peppermint water on prevention of nipple cracks in lactating primiparous women: a randomized controlled trialInt Breastfeed J · PMID 17442122

Diffuse Esophageal Spasm

Diffuse Esophageal Spasm Symptoms: improves

Diffuse Esophageal Spasm: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Diffuse Esophageal Spasm Symptoms	Improves (the measure goes down)		1 study	8 people
Studies that measured diffuse esophageal spasm symptoms Peppermint oil improves the manometric findings in diffuse esophageal spasmJ Clin Gastroenterol · PMID 11418786

General Gut Health

Gastric Emptying Rate: changes; see studies

General Gut Health: outcomes studied for Peppermint
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Gastric Emptying Rate	Changes; see studies		1 study	10 people

What the published studies found

3 automated readings

Automated reading of the published studies (Decosa evidence engine), for outcomes Dr. Grey has not graded yet. It is not a Dr. Grey grade and does not change one. How it is read

Bloating
The studies read are too weak to tell whether Peppermint changes bloating. They lean toward an improvement, which is not enough to claim one. The evidence is very weak.
3 studies counted of 8 read: 2 trials (89 people in the trials).
1. Study, 2025; patients with functional dyspepsia: improves. Updated document on the management of functional dyspepsia by the Asociación Española de Neurogastroenterologia y Motilidad (ASENEM) and Sociedad Española de Medicina Familiar y Comunitaria (semFYC)PubMed 39812003
2. Randomised trial, 2024; 32 people: improves. POCO induced less epigastric burning, bloating, and fullness The combination of L-menthol and caraway oil does not affect gastric function but increases hunger in healthy subjectsPubMed 39056471
3. Randomised trial, 2007; 57 people: improves. statistically significant reduction of the total irritable bowel syndrome symptoms score Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trialPubMed 17420159
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Memory
The 1 study read (144 people in all) mostly found an improvement in memory. The evidence is limited.
1 study counted of 3 read: 1 trial (144 people in the trials).
1. Randomised trial, 2008; 144 people; healthy volunteers: improves. Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylangPubMed 18041606
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Stress
The studies read are too weak to tell whether Peppermint changes stress. They lean toward an improvement, which is not enough to claim one. The evidence is very weak.
1 study counted of 9 read: 1 trial.
1. Randomised trial, 2026; patients with acute coronary syndrome: improves. stress levels (from 25.00 ± 5.14 to 17.18 The Impact of Peppermint Oil Aromatherapy on Hemodynamic Parameters, Anxiety, and Stress in Patients With Acute Coronary Syndrome: A Randomized Clinical TrialPubMed 42253765
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.

Key findings

Irritable Bowel Syndrome SymptomsIrritable Bowel Syndrome (IBS)Improves (the measure goes down)
Nausea SymptomsPregnancy and Delivery HealthImproves (the measure goes down)
HeadachesTension HeadacheImproves (the measure goes down)

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Grade A

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Studies cited

19 studies from PubMed

Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylangInt J Neurosci · PMID 18041606
Examination of the effectiveness of peppermint aromatherapy on nausea in women post C-sectionJ Holist Nurs · PMID 22034523
Peppermint oil: a treatment for postoperative nauseaJ Adv Nurs · PMID 9378876
An investigation into the use of aromatherapy in intrapartum midwifery practiceJ Altern Complement Med · PMID 10784271
A randomized trial of peppermint gel, lanolin ointment, and placebo gel to prevent nipple crack in primiparous breastfeeding womenMed Sci Monit · PMID 17767120
Aromatherapy with peppermint, isopropyl alcohol, or placebo is equally effective in relieving postoperative nauseaJ Perianesth Nurs · PMID 14770380
Early effects of peppermint oil on gastric emptying: a crossover study using a continuous real-time 13C breath test (BreathID system)J Gastroenterol · PMID 17653649
The effect of enteric-coated, delayed-release peppermint oil on irritable bowel syndromeDig Dis Sci · PMID 19507027
Enteric-coated, pH-dependent peppermint oil capsules for the treatment of irritable bowel syndrome in childrenJ Pediatr · PMID 11148527
Treating irritable bowel syndrome with peppermint oilBr Med J · PMID 389344
Enteric-coated peppermint-oil capsules in the treatment of irritable bowel syndrome: a prospective, randomized trialJ Gastroenterol · PMID 9430014
Treatment of irritable bowel syndrome with peppermint oil. A double-blind study with a placeboUgeskr Laeger · PMID 3061106
Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trialDig Liver Dis · PMID 17420159
Effectiveness of Oleum menthae piperitae and paracetamol in therapy of headache of the tension typeNervenarzt · PMID 8805113
Effect of peppermint and eucalyptus oil preparations on neurophysiological and experimental algesimetric headache parametersCephalalgia · PMID 7954745
Peppermint oil improves the manometric findings in diffuse esophageal spasmJ Clin Gastroenterol · PMID 11418786
Premedication with peppermint oil capsules in colonoscopy: a double blind placebo-controlled randomized trial studyActa Gastroenterol Belg · PMID 23082707
Efficacy of Peppermint oil in diarrhea predominant IBS - a double blind randomized placebo - controlled studyMymensingh Med J · PMID 23416804
Effect of peppermint water on prevention of nipple cracks in lactating primiparous women: a randomized controlled trialInt Breastfeed J · PMID 17442122

Evidence by condition

What the published studies found

Bloating

Memory

Stress

Key findings

Shop the evidence-backed picks

Studies cited

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