Antispasmodic (Natural — Calcium Channel Blocker in Intestinal Smooth Muscle) Pregnancy: There are no or limited data from use in pregnant women and animal studies are insufficient with respect to reproductive toxicity — use during pregnancy is not recommended. Should not be used during breast-feeding, as data suggest excretion of peppermint constituents/metabolites in human milk. Human fertility data have not been established.

Peppermint Oil

Brand names: Colpermin, Mintec

Peppermint oil is a herbal antispasmodic, supplied in enteric-coated capsules, used to relieve abdominal pain and bloating in irritable bowel syndrome.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One gastro-resistant capsule (peppermint oil 0.2 ml), for patients who weigh at least 40 kg

Route: Oral — swallow whole; must not be chewed, crushed or broken. Take 30 minutes before a meal with plenty of liquid

Frequency: Three times a day

Source SPC is Buscomint peppermint oil 0.2 ml gastro-resistant soft capsules. Duration of use: take until symptoms resolve, usually within one or two weeks; after two weeks the patient should seek medical advice if symptoms persist or deteriorate. Where symptoms are more persistent, treatment can be continued for periods of up to 3 months per treatment course. Renal impairment: no data are available for a dosing instruction. Paediatric population: contraindicated in children under 12 years of age and in adolescents who weigh less than 40 kg, because of safety concerns.

Dose adjustments

Renal

No data are available for a dosing instruction in case of impaired renal function.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance, to menthol or to any of the excipients
Patients with liver disease, cholangitis, achlorhydria, gallstones and any other biliary disorders
Patients with less than 40 kg bodyweight
Children under 12 years of age and adolescents with less than 40 kg bodyweight

Side effects

Heartburn (frequency not known); may be exacerbated in patients with pre-existing heartburn or hiatus hernia — discontinue treatment in these patients
Perianal burning (frequency not known)
Nausea and vomiting, dry mouth (frequency not known)
Allergic reaction to menthol with anaphylactic shock (frequency not known)
Muscle tremor, ataxia and headache (frequency not known)
Abnormal smell of faeces and abnormal urine odour of menthol, dysuria (frequency not known)

Interactions

No interaction studies have been performed (SPC 4.5)
Food or antacids administered at the same time could cause early release of the capsule content
Other medicinal products used to decrease stomach acid — histamine-2 blockers and proton pump inhibitors — may cause premature dissolution of the enteric coating and should be avoided

Clinical monograph

How it works

Its principal constituent, menthol, blocks calcium channels in intestinal smooth muscle, producing relaxation and reducing spasm.

Prescribing in practice

Capsules are enteric-coated to release in the small bowel, so they must be swallowed whole and not broken or chewed, otherwise oesophageal irritation and heartburn may occur.
It is recommended by NICE as an option for the symptomatic relief of pain and spasm in irritable bowel syndrome.
Use cautiously in gastro-oesophageal reflux, as it may relax the lower oesophageal sphincter and worsen symptoms.

Monitoring

No routine laboratory monitoring is required; review symptomatic response and tolerability at follow-up.

Counselling the patient

Swallow the capsule whole with water and do not chew it.
Take it before meals, and report persistent heartburn or perianal irritation.

Evidence & guidelines

NICE recommends antispasmodics including peppermint oil as a first-line option for symptom control in irritable bowel syndrome.

Reference: NICE CG61 Irritable Bowel Syndrome; SPC Colpermin; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways