Antimuscarinic antispasmodic Pregnancy: Epidemiological studies (doses up to 40 mg/day) have not shown an increased risk of foetal abnormality in the first trimester, and animal studies revealed no impaired fertility or foetal harm; however teratogenicity cannot be excluded with absolute certainty, so use in pregnancy only if the benefit outweighs the risk. Breast-feeding: excretion in human milk is unknown - exercise caution.

Dicycloverine hydrochloride

Brand names: Merbentyl

Dicycloverine hydrochloride is an antimuscarinic antispasmodic used for the symptomatic relief of smooth-muscle spasm in irritable bowel syndrome and other functional gastrointestinal disorders.

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: 10-20 mg

Route: Oral

Frequency: Three times daily, before or after meals

SPC §4.2 states this dose for adults and children over 12 years. Children 2-12 years: 10 mg three times daily (a dicycloverine hydrochloride syrup is available for this age group) - flat dose, not weight-based; verify paediatric use against a children's formulary. Source is the Dicycloverine hydrochloride 10 mg Tablets SPC (oral use). Use with caution in patients with or suspected of having glaucoma or prostatic hypertrophy, and in hiatus hernia with reflux oesophagitis (§4.4). Tablets contain lactose monohydrate.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Known idiosyncrasy to dicycloverine hydrochloride

Side effects

Dry mouth and thirst
Dizziness
Fatigue, sedation, blurred vision (rare)
Constipation, anorexia, nausea and vomiting (rare)
Rash, headache, dysuria (rare)

Interactions

No interaction studies have been performed (SPC §4.5)

Clinical monograph

How it works

It relaxes gastrointestinal smooth muscle through antimuscarinic (anticholinergic) action and a direct relaxant effect, reducing painful gut spasm.

Prescribing in practice

As an antimuscarinic it is contraindicated or used cautiously in conditions such as paralytic ileus, gastrointestinal obstruction, urinary retention, prostatic enlargement and angle-closure glaucoma.
Antimuscarinic load means caution in older people who are more susceptible to confusion, constipation and urinary effects.
Anticholinergic side effects such as dry mouth, blurred vision and constipation are common.

Monitoring

No specific monitoring is required; review symptom control and reconsider the diagnosis if abdominal symptoms change or alarm features appear.

Counselling the patient

Take to relieve abdominal cramps and spasm.
It may cause a dry mouth, blurred vision or constipation; tell your prescriber if these are troublesome.
Seek review if you develop difficulty passing urine.

Evidence & guidelines

NICE guidance on irritable bowel syndrome supports antispasmodics, including antimuscarinic agents, for relief of abdominal pain and spasm.

Reference: NICE NG61; BSG IBS guideline; 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.

Pathways