An essential oil distilled from peppermint leaf, dominated by menthol and menthone. For gut use it is supplied in enteric-coated or delayed-release capsules designed to bypass the stomach.
Peppermint oil is the strongest evidence case in this catalogue for a genuinely botanical product. Multiple randomised trials and meta-analyses find enteric-coated peppermint oil reduces global symptoms and abdominal pain in irritable bowel syndrome compared with placebo, and it appears in several national gastroenterology guidelines as an option. Reflux is the main limitation, and the enteric coating exists precisely because uncoated oil relaxes the oesophageal sphincter.
Capsules state peppermint oil content, commonly 0.2 mL (about 180–187 mg) per capsule — a product without this marker may not resemble what was studied.
Regulation: Available as a licensed medicine for irritable bowel syndrome in several countries and as a supplement in others. It appears as a conditional recommendation in some gastroenterology society guidelines, which is unusual for a botanical.
What the research used
The amounts, forms and durations published trials of Peppermint oil actually administered.
These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.
Studied for Irritable bowel syndrome
180–750 mg
Moderate
Enteric-coated peppermint oil, two to three times daily · 4–12 weeks
Trials used enteric or delayed-release capsules specifically; plain peppermint oil, tea or non-coated softgels have not been shown equivalent and are more likely to cause reflux.
Studied for Tension headache, topical
10 %
Limited
Peppermint oil in ethanol applied to the forehead and temples · Single application
A concentration applied to skin from a small older German trial, not an oral dose.
This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.
When it was taken
Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.
None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.
⏳On an empty stomach
Limited
Trials dose it 30 to 60 minutes before meals so the enteric coating passes the stomach before food arrives. This is formulation pharmacology rather than a tested comparison of schedules, but it is the reason the timing instruction exists.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.
The evidence in depth
Best supported: Strong
What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.
Multiple randomised trials, pooled in several meta-analyses, report that enteric-coated peppermint oil reduces global symptoms and abdominal pain in irritable bowel syndrome compared with placebo. Trials are short and mostly small, so the durability of the effect is less clear than its existence, and it applies to the enteric-coated form rather than peppermint generally.
What may be going on: Menthol blocks calcium channels in intestinal smooth muscle, producing an antispasmodic effect.
Strong evidence. Consistent findings across multiple good-quality human studies.
There is not enough human research to support peppermint oil and exercise performance. The few small studies are inconsistent and often use inhaled aroma with no blinding.
Not enough evidence. Not enough human research to say anything useful yet.
Deep research mode adds each paper’s own conclusion and stated limitations.
Things to know
Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.
Worth knowing
Worsens reflux, especially uncoated
Peppermint oil relaxes the lower oesophageal sphincter, and heartburn is the most common reason people stop it. Anyone with gastro-oesophageal reflux or a hiatus hernia should be cautious, and uncoated preparations are worse.
Avoid
Not for infants and young children
Menthol applied to the face or chest of infants can cause laryngospasm and breathing difficulty, and undiluted essential oil taken by mouth is toxic to small children.
Peppermint oil inhibits CYP3A4 in laboratory work, which may raise levels of some medicines. Acid-suppressing drugs can also dissolve the enteric coating prematurely, releasing oil in the stomach.
Worth knowing
Gallstones and bile duct obstruction
Peppermint oil is conventionally avoided in gallstone disease, bile duct obstruction and severe liver disease.
Allergy
Perianal burning and rash
Burning on defecation is a recognised effect of enteric-coated capsules, and allergic rash to menthol occurs occasionally.
In the food catalogue
The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.