Peppermint

What is peppermint?

Peppermint is a natural cross between water mint and spearmint. Its leaves and the essential oil distilled from them are rich in menthol, which produces the familiar cooling sensation. The National Center for Complementary and Integrative Health notes that peppermint has been used for digestive complaints since ancient times and is promoted today for irritable bowel syndrome, indigestion, headaches and nausea.

In oral care, peppermint is mainly a flavoring in toothpaste, chewing gum and mouthwash, and menthol is one of the essential oils in some antiseptic rinses.

What the research says

The best evidence for peppermint oil is digestive. NCCIH reports that a 2022 review of 10 studies found peppermint oil better than placebo for overall IBS symptoms and abdominal pain, with mostly mild side effects such as reflux and indigestion.

For the mouth, research centers on essential oil mouthrinses that combine menthol with thymol, eucalyptol and methyl salicylate. A meta-analysis of 29 trials of six months or longer found that adding such a rinse to brushing and flossing substantially increased the odds of healthy gum sites and plaque-free sites. An independent review of 16 trials also found lower plaque and gingivitis scores with essential oil mouthwashes than with placebo, though study quality was moderate to low. These results apply to twice-daily rinses with a specific formula, not to peppermint oil alone or to a small amount used as a flavoring in a tablet.

For temporary bad breath, MedlinePlus notes that fresh parsley or a strong mint is often effective, while mouthwashes do not treat the underlying cause.

How it’s used in supplements

In digestive supplements, peppermint oil comes in enteric-coated capsules designed to release in the intestine. In chewable and dental supplements it is usually a flavor in “other ingredients,” with no stated amount, and its effect is mostly sensory: it makes the mouth feel fresh. Peppermint oil is generally safe in normal amounts, but it can cause heartburn, nausea or, rarely, allergic reactions, and NCCIH advises not applying it to the faces of infants or young children.

If your goal is fresher breath or less plaque, an evidence-based mouthrinse used as directed, along with brushing, flossing and tongue cleaning, is a more direct option than a supplement that contains peppermint as a flavor. People with reflux may find that peppermint products worsen heartburn. Peppermint tea made from the leaves appears to be safe for most adults, according to NCCIH.