Caraway and Mint Capsules for Indigestion: Which Formulation Was Tested?

Before comparing capsules, locate the symptom. Upper-belly burning, discomfort or fullness after a small meal fits the indigestion symptom list. Heartburn can occur alongside it, but NIDDK¹ describes heartburn and indigestion as separate conditions.¹

That distinction matters when a bottle’s promise simply says “digestive support.” Write down whether you want help with early fullness, upper-belly pain, chest burning or a change in bowel movements. A study’s answer depends on what it measured.

The 2019 capsule contained L-menthol, rather than whole peppermint oil

The 2019 trial² analyzed 95 adults with functional dyspepsia. Each capsule contained 25 mg caraway oil and 20.75 mg L-menthol, delivered in coated microspheres. Participants took two capsules twice daily for four weeks; usual indigestion medicines could continue.²

At 24 hours, post-meal pressure, heaviness and fullness improved more than with placebo. Upper-belly pain did not show a statistically clear difference. Across the full group, symptom comparisons at two and four weeks were not statistically significant.²

A favorable four-week finding came from a smaller, higher-pain subgroup. The study made numerous comparisons without adjusting the significance threshold. That limits how confidently the subgroup result can guide treatment. IM HealthScience funded the trial, and authors disclosed consulting or company roles.²

A peppermint-oil combination produced different four-week findings

The 2017 Menthacarin trial³ randomized 114 outpatients to the combination or placebo for four weeks, one capsule twice daily. It measured pain and discomfort with the Nepean Dyspepsia Index.³

Reported mean improvements were 7.6 versus 3.4 points for pain, and 3.6 versus 1.3 for discomfort, favoring Menthacarin. These were questionnaire changes, not percentages cured. The original abstract reports advantages at two and four weeks.³

This result cannot tell you that Menthacarin beats the L-menthol formulation: participants were not randomized between those two products. Different scales, entry criteria and treatment designs make a comparison of their headline numbers unreliable.

The pooled evidence supports a short-term benefit

The 2023 Cochrane review included three peppermint/caraway comparisons with 305 participants, including the 2019 and 2017 trials. At four weeks, the pooled likelihood of clinical improvement was higher with treatment: risk ratio 1.53, with a 95% confidence interval of 1.30 to 1.81. The review rated that evidence moderate certainty, reduced because of risk of bias.⁴

That ratio does not mean 53% of everyone taking a capsule will improve. It compares improvement rates between treatment and placebo groups. Nor does pooling establish that every formulation works equally well. The review searched through December 2022 and provides a short-term assessment, rather than evidence of indefinite benefit.⁴

The newer eight-week study had no placebo group

A study published online in December 2025, in a 2026 journal volume, treated 126 people for eight weeks with Menthacarin. Each capsule contained 90 mg peppermint oil and 50 mg caraway oil, taken twice daily. Symptoms improved, but everyone received the product.⁵

Participants had abdominal pain/cramps or bloating without an identified organic cause; constipation was excluded. This was a broader symptom population than a trial restricted to functional dyspepsia. Without a comparison group, changes during treatment cannot establish how much improvement the capsules caused.⁵

Dr. Willmar Schwabe funded the study and publication. Its longer observation period adds information about use and tolerability, but does not supply a new eight-week placebo comparison.⁵

Match the product, then check whether mint suits you

NCCIH⁶ lists heartburn, nausea and abdominal pain among possible oral peppermint-oil side effects. Coating can reduce the likelihood of heartburn; it does not make every product suitable for someone with reflux. There is little research on peppermint leaf, and medicinal amounts during pregnancy or breastfeeding lack adequate safety information.⁶

Bring the actual package to a pharmacist: ingredient amounts, coating, other ingredients and directions all matter. Mint tea and an essential-oil bottle are different preparations from the trial capsules. Avoid converting the research into a homemade oil mixture.

For a record of meals, symptom timing and supplements, the Belly Clock in Chapter 4 of Bloated by Dinner gives you a way to describe what happens before changing products. Our peppermint capsule article for IBS addresses a different treatment question.

Arrange medical assessment if indigestion does not improve. Trouble swallowing, unexplained weight loss, frequent vomiting or persistent swelling also need assessment. Bloody vomit, black tar-like stools, severe constant abdominal pain, chest pain or shortness of breath require help right away, rather than another supplement trial.¹