Antimotility opioid
Loperamide hydrochloride
Brand names: Imodium
Adult dose
Dose: Acute diarrhoea: 4mg PO initially, then 2mg after each loose stool (max 16mg/24h, OTC max 12mg/24h)
Route: PO
Frequency: PRN
Clinical pearls
- Acute diarrhoea, chronic IBS-D, ileostomy output management
- Avoid in suspected infective enteritis with fever/bloody stools
Contraindications
- Acute UC / pseudomembranous / antibiotic-associated colitis
- Acute dysentery (bloody diarrhoea + fever)
- Children <12 (most preparations)
- Bacillary dysentery
Side effects
- Constipation
- Abdominal cramps
- Drowsiness (rare at therapeutic doses)
- Cardiac toxicity (QT prolongation, torsades) at high/abuse doses (MHRA)
- Paralytic ileus
Interactions
- P-gp inhibitors (raise levels, CNS effects)
- Ritonavir/quinidine
- CYP3A4 inhibitors
Reference: BNF; NICE CKS; MHRA Drug Safety Update; https://bnf.nice.org.uk/drugs/loperamide-hydrochloride/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- Morphine Milligram Equivalents (MME) Calculator · Pain / Opioids
- Opioid Conversion / Equianalgesic Guide · Pain Management
- Numeric Rating Scale (NRS) Pain Assessment and Management · Pain Management
- Finnegan Neonatal Abstinence Scoring Tool (FNAST) · Neonatal Abstinence Syndrome
- Modified Finnegan Neonatal Abstinence Score (NAS) · Neonatal
- Withdrawal Assessment Tool (WAT-1) for Paediatric Iatrogenic Withdrawal · Critical Care
Pathways
- Lower Gastrointestinal Bleed · BSG 2019; NICE NG141
- Variceal Upper GI Bleed · BSG 2015; Baveno VII (2022)
- Spontaneous Bacterial Peritonitis (SBP) · BSG / EASL 2018
- Hepatorenal Syndrome · EASL 2018; ICA 2015
- Hepatic Encephalopathy · EASL 2014; West Haven criteria
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021