Loperamide

Peripheral Opioid Agonist·Gastrointestinal - IBD & Antidiarrhoeals

Acute uncomplicated diarrhea, high-output ileostomies

PBSANTIDIARRHOEALGastro-Stop, Imodium2 mg tabletS4+1

Max Dose

16 mg/day

Half-life

11 h

Bloody Stool

CONTRAIND.

Systemic Abs.

POOR

Rapid Summary

Overview

Potent peripheral opioid receptor agonist. Slows gut motility and increases water reabsorption. The gold standard for non-infectious or traveller's diarrhea.

Maximum Dose

Max 16 mg/day (8 capsules).

Clinical Focus

Never use in severe inflammatory or bloody diarrhea (dysentery), as paralyzing the gut risks toxic megacolon.

Bottom Line

Loperamide is the standard antidiarrhoeal for acute non-infectious diarrhoea, but must never be used in bloody/infectious diarrhoea or C. difficile as it can precipitate toxic megacolon.

Formulation & Access

Brand Names

Gastro-Stop, Imodium

Oral Routes

Capsules/Tablets (2 mg).

Prescribing & PBS

Pharmacy Medicine (S2). PBS available for chronic conditions.

Indications & Use

Primary

PBSTGA

Acute uncomplicated diarrhea, high-output ileostomies.

Clinical Place

First-line symptomatic relief for high-volume diarrhea once C. diff and severe bacterial infections are ruled out.

Quick reference

Class & Role

Peripheral Opioid Agonist — Potent peripheral opioid receptor agonist.

Route / Formulation

Capsules/Tablets (2 mg). (Gastro-Stop, Imodium)

Usual Dose & Max

PO 4 mg STAT, then 2 mg after every unformed stool. Max 16 mg/day.

Key Indication Doses

Acute Diarrhea: PO 4 mg STAT, then 2 mg after every unformed stool. Max 16 mg/day. Chronic Diarrhea (e.g. Stoma): PO 2-4 mg BD to QID (Titrated to stool consistency).

Best Uses

Loperamide is the standard antidiarrhoeal for acute non-infectious diarrhoea, but must never be used in bloody/infectious diarrhoea or C. difficile as it can precipitate toxic megacolon.

Avoid / Cautions

Dysentery (fever + bloody diarrhea), C. difficile enterocolitis, acute ulcerative colitis flare, children < 12 years. Pregnancy Category B3. Minimal systemic absorption makes it generally safe.

Key Risks

Gastrointestinal: Severe constipation, abdominal cramping, paralytic ileus. CRITICAL — Toxic megacolon (if used inappropriately in severe colitis). Cardiovascular: At massive supratherapeutic doses (abuse), causes severe QTc prolongation and Torsades de Pointes.

Key Interactions

P-gp inhibitors (e.g., Verapamil, Ketoconazole) can theoretically push loperamide across the blood-brain barrier, causing opioid sedation, but rare at normal doses.

Monitoring

Cease immediately if abdominal distension occurs. Monitor stool chart. Check U&E if diarrhea has been profound (hypokalemia).

Clinical Pearl

If a patient has a fever and bloody stool (e.g., Salmonella, Shigella, Campylobacter), do NOT give Loperamide. Paralyzing the gut traps the invasive bacteria, allowing them to erode through the bowel wall and cause sepsis or toxic megacolon.

Access

Gastro-Stop, Imodium2 mg tablet

Brand: Gastro-Stop, Imodium
Formulation: Capsules/Tablets (2 mg)

Loperamide

Peripheral Opioid Agonist·Gastrointestinal - IBD & Antidiarrhoeals

Acute uncomplicated diarrhea, high-output ileostomies

PBSANTIDIARRHOEALGastro-Stop, Imodium2 mg tabletS4+1

Max Dose

16 mg/day

Half-life

11 h

Bloody Stool

CONTRAIND.

Systemic Abs.

POOR

Rapid Summary

Overview

Potent peripheral opioid receptor agonist. Slows gut motility and increases water reabsorption. The gold standard for non-infectious or traveller's diarrhea.

Maximum Dose

Max 16 mg/day (8 capsules).

Clinical Focus

Never use in severe inflammatory or bloody diarrhea (dysentery), as paralyzing the gut risks toxic megacolon.

Bottom Line

Loperamide is the standard antidiarrhoeal for acute non-infectious diarrhoea, but must never be used in bloody/infectious diarrhoea or C. difficile as it can precipitate toxic megacolon.

Formulation & Access

Brand Names

Gastro-Stop, Imodium

Oral Routes

Capsules/Tablets (2 mg).

Prescribing & PBS

Pharmacy Medicine (S2). PBS available for chronic conditions.

Indications & Use

Primary

PBSTGA

Acute uncomplicated diarrhea, high-output ileostomies.

Clinical Place

First-line symptomatic relief for high-volume diarrhea once C. diff and severe bacterial infections are ruled out.

Quick reference

Class & Role

Peripheral Opioid Agonist — Potent peripheral opioid receptor agonist.

Route / Formulation

Capsules/Tablets (2 mg). (Gastro-Stop, Imodium)

Usual Dose & Max

PO 4 mg STAT, then 2 mg after every unformed stool. Max 16 mg/day.

Key Indication Doses

Acute Diarrhea: PO 4 mg STAT, then 2 mg after every unformed stool. Max 16 mg/day. Chronic Diarrhea (e.g. Stoma): PO 2-4 mg BD to QID (Titrated to stool consistency).

Best Uses

Loperamide is the standard antidiarrhoeal for acute non-infectious diarrhoea, but must never be used in bloody/infectious diarrhoea or C. difficile as it can precipitate toxic megacolon.

Avoid / Cautions

Dysentery (fever + bloody diarrhea), C. difficile enterocolitis, acute ulcerative colitis flare, children < 12 years. Pregnancy Category B3. Minimal systemic absorption makes it generally safe.

Key Risks

Key Interactions

P-gp inhibitors (e.g., Verapamil, Ketoconazole) can theoretically push loperamide across the blood-brain barrier, causing opioid sedation, but rare at normal doses.

Monitoring

Cease immediately if abdominal distension occurs. Monitor stool chart. Check U&E if diarrhea has been profound (hypokalemia).

Clinical Pearl

Access

Gastro-Stop, Imodium2 mg tablet

Brand: Gastro-Stop, Imodium
Formulation: Capsules/Tablets (2 mg)