Lamiaceae
Mentha × piperita
Peppermint
- Part used
- leafoil
- Native range
- A hybrid of garden origin, from Mentha aquatica crossed with Mentha spicata; naturalised widely
- Morphology
- A sterile perennial hybrid to about eighty centimetres, square-stemmed, with dark green toothed leaves often tinged purple and blunt spikes of pale mauve flowers. Being sterile it spreads by runners, so a patch is usually one clone.
What is in it
Evidence
Enteric-coated peppermint oil has good trial support for irritable bowel syndrome and appears in clinical guidance. There is also reasonable evidence for reducing spasm during endoscopy and barium studies. The tea has not been tested to anything like the same standard.
Safety
The leaf and tea are benign. The concentrated oil is not the same product: it relaxes the lower oesophageal sphincter and worsens reflux, which is why the clinical preparations are enteric-coated to bypass the stomach. Undiluted oil is irritant, and menthol applied to the face or chest of infants can cause apnoea and laryngospasm.
Interactions: May raise levels of drugs metabolised by CYP3A4; Worsens gastro-oesophageal reflux
Regulatory: Permitted as a food and as a listed medicine ingredient. Enteric-coated preparations are registered medicines in several countries.
How the traditions classify it
Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.
Historical use
Recorded as a distinct plant only in the late seventeenth century in England, though mints generally are ancient. Used for indigestion, colic, nausea and headache.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Peppermint is one of the few entries here where a traditional use survived proper testing, and the reason is mechanical rather than mysterious: menthol relaxes smooth muscle, and irritable bowel syndrome is a smooth-muscle problem.
It also demonstrates why the form is the medicine. A cup of peppermint tea is pleasant and untested. Enteric-coated oil capsules are a clinical intervention with guideline support. Plain oil swallowed neat makes reflux worse. Same plant, three different products, three different answers.
Its cooling sensation is not temperature. Menthol activates TRPM8, the receptor that detects actual cold — which is a small, checkable example of why four unconnected traditions all built medicine on hot and cold.
Nomenclature verified against GBIF backbone taxonomy.