ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Antispasmodic (Anticholinergic) Pregnancy: Compatible — widely used for IBS in pregnancy; no significant teratogenicity. Monitor for anticholinergic effects in neonate if used near delivery.

Dicycloverine Hydrochloride (Dicyclomine)

Brand names: Merbentyl

Adult dose

Dose: 10–20mg three times daily before meals. Increase to 40mg three to four times daily if needed and tolerated.
Route: Oral
Frequency: Three to four times daily before meals
Max: 160mg/day
For IBS-associated abdominal pain and colic. Anticholinergic mechanism — similar to hyoscine but crosses BBB more readily. Take 30 minutes before meals. Second-line after mebeverine (due to anticholinergic side effects).

Paediatric dose

Route: Oral
Frequency: Three times daily
Max: 10mg per dose
BNF for Children: contraindicated in infants <6 months (apnoea risk). 6 months–2 years (off-label specialist use only): 5–10mg TDS. Children ≥2 years: 10mg TDS. Source: BNF for Children 2024.

Dose adjustments

Renal

Use with caution in renal impairment.

Hepatic

Use with caution in hepatic impairment.

Clinical pearls

  • Merbentyl contraindicated in infants <6 months: cases of respiratory distress and apnoea reported — absolute contraindication.
  • Anticholinergic burden: dicycloverine contributes to anticholinergic load — use with caution in elderly (confusion, falls, urinary retention). Mebeverine is preferred in elderly patients.
  • NICE CG61 (IBS): mebeverine or hyoscine butylbromide are preferred first-line antispasmodics. Dicycloverine is an alternative.
  • Dry mouth management: sugar-free chewing gum or saliva substitute (e.g., BioXtra) — improve compliance.

Contraindications

  • Infants under 6 months (risk of respiratory distress and apnoea)
  • Myasthenia gravis
  • Paralytic ileus
  • Narrow-angle glaucoma
  • Urinary retention (benign prostatic hyperplasia — relative)

Side effects

  • Dry mouth (very common — anticholinergic)
  • Blurred vision
  • Urinary retention
  • Constipation
  • Tachycardia
  • Confusion / drowsiness (CNS anticholinergic — penetrates BBB)
  • Apnoea in infants (contraindicated <6 months)

Interactions

  • Other anticholinergics: additive effects — avoid polypharmacy in elderly
  • Metoclopramide / domperidone: antagonism of prokinetic effect

Monitoring

  • Symptom response
  • Anticholinergic side effects (especially in elderly)

Reference: BNFc; BNF 90; NICE CG61 Irritable Bowel Syndrome; SPC Merbentyl. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Drugs
Pathways