You probably already have peppermint somewhere in your kitchen. Most people do — in a teabag, a packet of leaves, a mint chocolate bar consumed without much thought. The plant in its proper form is almost nothing like any of these things.

Mentha × piperita is a hybrid of watermint and spearmint, and it is a plant that has been used medicinally for as long as records of human medicine exist. The ancient Egyptians used it. Hippocrates wrote about it. It appears in virtually every European herbal tradition from the medieval period onwards. And yet its modern reputation is primarily as a flavouring agent — for confectionery, toothpaste, chewing gum — rather than as the seriously useful medicine it is.

The evidence for peppermint's effectiveness in a range of common conditions is among the most robust in herbal medicine. It is the herb with which to begin if you are new to the home apothecary and want something that will reliably work.

Digestion: The Obvious Starting Point

The case for peppermint in digestive complaints is well established. Peppermint oil has been the subject of multiple meta-analyses examining its effectiveness in irritable bowel syndrome, and the results are consistently positive. A 2014 meta-analysis published in the Journal of Clinical Gastroenterology found that peppermint oil was significantly more effective than placebo in reducing IBS symptoms including abdominal pain, bloating and altered bowel function.

The mechanism is primarily menthol's action as a calcium channel blocker in the smooth muscle of the intestinal wall — in simple terms, it relaxes the muscle, reducing cramping and spasm. This is the same mechanism that makes enteric-coated peppermint oil capsules effective for IBS, and it is also active, in milder form, in a strong cup of peppermint tea.

For a medicinal-strength peppermint tea, use a heaped teaspoon of dried peppermint leaf per cup, cover the cup to retain the volatile oils, and steep for ten full minutes. Drink after meals for digestive support or at the first sign of bloating or cramping. The taste is powerful and unmistakably medicinal — very different from a supermarket peppermint teabag.

Headaches and Migraines

The comparison between peppermint oil and common analgesics for tension headaches is one of the more striking results in the herbal medicine literature. A 1996 study published in Cephalalgia — a peer-reviewed headache journal — found that a ten percent peppermint oil preparation applied to the forehead was as effective as 1,000mg of paracetamol in reducing tension headache pain, and worked faster.

Subsequent studies have replicated this result. The mechanism involves menthol's effect on the TRPM8 receptor, which produces the sensation of cooling — this activates the same neural pathway that cold packs do, reducing the perception of pain without affecting the underlying cause.

A simple peppermint headache balm can be made by adding five drops of peppermint essential oil to a teaspoon of solid coconut oil or beeswax. Apply to the temples, the forehead and the back of the neck at the first sign of tension. Keep away from the eyes — menthol is intensely irritating to mucous membranes.

Nausea

Peppermint's effectiveness against nausea is primarily olfactory — meaning it works through the sense of smell. Inhaling the scent of peppermint has been shown in several clinical settings to reduce nausea, including postoperative nausea, chemotherapy-related nausea and pregnancy nausea. A 2013 study in the Journal of Alternative and Complementary Medicine found that peppermint oil inhalation significantly reduced nausea intensity in postoperative patients compared to a saline control.

The practical application is to carry a small inhaler filled with peppermint essential oil — these are available inexpensively and can be refilled as needed. When nausea strikes, opening the inhaler and breathing slowly through it for a minute is often enough to significantly reduce the sensation. A cup of peppermint tea has a similar, if slower, effect.

Peppermint tea can also help with nausea associated with indigestion or overeating, where the relaxant effect on the stomach muscle contributes alongside the olfactory response.

Respiratory Support

Menthol acts as a natural decongestant by activating the same cold receptors in the nasal passages that respond to physically cold air, creating the sensation of easier breathing. This does not actually open the airways in the way a pharmaceutical decongestant does — but the perception of easier breathing can be genuinely helpful during colds and catarrh.

Steam inhalation is the most effective delivery method: add five drops of peppermint essential oil to a bowl of just-boiled water, lean over the bowl with a towel over your head, and breathe through your nose for five minutes. This is also effective for chest congestion — the volatile compounds reach the bronchial passages through the airways.

One important safety note: peppermint essential oil and preparations containing significant concentrations of menthol should not be applied near the face of children under two years old, and should be used with caution around infants generally. The menthol can cause a reflex slowing of breathing in very young children. This is not a risk with properly diluted peppermint tea or with the herb used in cooking.

Growing Peppermint Responsibly

Peppermint must always be grown in a container. This is not a preference — it is a hard rule. Planted in open ground, it will spread by underground runners across a surprisingly large area in a single season, and it is extremely difficult to eradicate once established. In a pot it is excellent: vigorous, productive, and easy to manage.

Choose a pot at least 30cm in diameter and avoid placing it directly on soil where runners could escape through the drainage holes. A terracotta pot is better than plastic as it allows some regulation of soil moisture — peppermint likes consistent moisture but not waterlogging.

Harvest for drying just before the plant begins to flower, cutting stems to about a third of their length and leaving enough for the plant to recover. Dry quickly at low temperature to preserve the volatile oils — a dehydrator at 35°C for two to four hours, or a warm, well-ventilated room away from direct light. Properly dried peppermint should smell powerfully of menthol and retain its green colour.

The most useful herb is often the one already growing in the corner of the garden, waiting to be taken seriously.

— Moss & Lore —