Functional abdominal pain is one of the most common—and challenging—complaints in pediatric practice. As integrative medicine practitioners, many of us turn to evidence-based herbal options like peppermint oil (PMO), particularly for children with functional abdominal pain (FAP) or irritable bowel syndrome (IBS), where traditional therapies may offer limited relief. While PMO is widely used for its antispasmodic and soothing effects, pediatric-specific studies have historically lagged behind the adult literature. That’s why this new randomized trial by Shulman et al., published in The British Journal of Clinical Pharmacology (2025), is such a valuable contribution.
This study builds directly on the group’s earlier work and focuses on clarifying both the pharmacokinetics (how the body absorbs and processes menthol) and physiological effects on gut motility in children. Forty children aged 7–12 with Rome IV-defined FAP were randomized to receive either 540 mg or 900 mg of enteric-coated PMO daily for one week. All participants underwent objective GI motility assessments via a wireless motility capsule (SmartPill®), along with 24-hour menthol blood level monitoring after a single dose.
The results are illuminating: menthol levels peaked at around 2.5 hours post-dose and increased proportionally with higher PMO doses. While neither dose significantly altered gastric or small bowel transit, the higher 900 mg dose significantly decreased contraction frequency in the colon (p = 0.002) and across the whole gut (p = 0.02). Importantly, the study also found that higher menthol exposure (as measured by AUC) correlated with longer colonic and whole bowel transit times—suggesting a dose-responsive, systemic effect on gut motility.
These findings add a mechanistic layer to what earlier studies had shown symptomatically. For example, a 2001 double-blind RCT by Kline et al. demonstrated that children with IBS who took 187 mg of PMO three times daily had significantly greater improvement in abdominal pain compared to placebo. However, that trial didn’t evaluate how or why peppermint oil worked. Shulman’s team now provides that missing physiological link: enteric-coated PMO slows down colonic contractility, which may relieve pain by reducing spasm and non-propulsive contractions.
What’s especially helpful about this study is the attention to dose escalation and systemic absorption, an area often overlooked in herbal medicine research. Prior studies suggested that 180 mg PMO taken three times daily might not be enough to reach a therapeutic threshold for motility effects in children. This study confirms that menthol exposure increases with dose and that a higher daily intake—up to 900 mg—may be more effective in achieving the gut-slowing effects associated with pain relief.
Clinically, this study supports the thoughtful use of 180 mg enteric-coated capsules, given three to five times daily depending on patient size, tolerance, and symptom pattern. No significant side effects were reported, though care should still be taken in children with reflux, as menthol can sometimes lower esophageal sphincter pressure.
Of course, there are limitations. The study was not placebo-controlled, and it was not designed to assess symptom improvement as a primary endpoint. But as a rigorously conducted pharmacokinetic and pharmacodynamic trial, it fills a major gap in the pediatric integrative medicine evidence base.
For clinicians interested in replicating the study’s protocol, it’s helpful to know that the researchers used Pepogest® by Nature’s Way, a commercially available enteric-coated peppermint oil supplement. Each capsule contains 180 mg of peppermint oil, and the study used doses of either 540 mg/day (one capsule three times daily) or 900 mg/day (one capsule five times daily). Because this product was used in both the current study and prior pharmacokinetic research by the same group, it represents a practical, evidence-aligned option for clinical use. Pepogest is widely accessible through online retailers and health food stores, and its consistent formulation and enteric coating make it a reliable choice when recommending peppermint oil for children with functional abdominal pain.
In the broader context, this trial complements existing pediatric RCTs that showed benefit of PMO in reducing pain, while taking a crucial step forward by helping us understand the how. For integrative clinicians, this study not only affirms a commonly used therapy but also gives us more clarity on how to dose, what effects to expect, and how to talk about the evidence with families.
Citation: Shulman RJ, Chumpitazi BP, Gonzalez D, et al. Randomized trial: Peppermint oil (menthol) pharmacokinetics in children and effects on gut motility in children with functional abdominal pain: 540 mg vs. 900 mg dose comparison. Br J Clin Pharmacol. 2025. doi:10.1002/bcp.70097