Loperamide
IMODIUM
Pronunciation: loe-PER-a-mide
“Loops Immobilize peristalsis”
What it isPeripherally restricted mu agonist slowing gut transit; diarrhea.
Why this oneP-glycoprotein keeps it out of the CNS, so it controls diarrhea without euphoria or dependence at normal doses.
What limits itAt the supratherapeutic doses used for abuse it saturates P-gp and causes torsades and death. Avoid in inflammatory or invasive colitis.
Pearls
- In IBS-D, cuts stool frequency but not pain or bloating.
FDA-approved for
- diarrhea (1976)
Principal riskTorsades at the supratherapeutic doses used for abuse
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityTherapeutic CNS effects are minimal, but high-dose misuse can cause fatal sodium/potassium-channel cardiotoxicity.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Acute nonspecific diarrhea | Adults & pediatric ≥13 yr | 4 mg, then 2 mg after each unformed stool | 16 mg/day | |
| Chronic diarrhea associated with inflammatory bowel disease | Adults | 4 mg, then 2 mg after each unformed stool until controlled | 4–8 mg/day (single or divided doses) | 16 mg/day |
| Acute nonspecific diarrhea | Pediatric 2–5 yr (13–20 kg) | 1 mg TID on day 1 (non-prescription liquid 1 mg/5 mL) | Then 1 mg/10 kg after a loose stool only | 3 mg/day |
| Acute nonspecific diarrhea | Pediatric 6–8 yr (20–30 kg) | 2 mg BID on day 1 | Then 1 mg/10 kg after a loose stool only | 4 mg/day |
| Acute nonspecific diarrhea | Pediatric 8–12 yr (>30 kg) | 2 mg TID on day 1 | Then 1 mg/10 kg after a loose stool only | 6 mg/day |
Renal No dosage adjustment required
Hepatic Use with caution (exposure may be increased); monitor for CNS toxicity
Avoid doses higher than recommended (serious cardiac adverse reactions). Chronic diarrhea: if no improvement after 16 mg/day for at least 10 days, further administration is unlikely to help. Also indicated to reduce ileostomy discharge volume.
Instructions
- Give appropriate fluid and electrolyte replacement as needed
Available strengths
- cap 1, 2 mg
- tab 2 mg
- sol 1 mg/5 mL
- susp 1 mg/7.5 mL
Contraindications
- Pediatric patients <2 years (respiratory depression, serious cardiac adverse reactions)
- Abdominal pain without diarrhea
- Acute dysentery (blood in stools, high fever)
- Acute ulcerative colitis
- Bacterial enterocolitis from invasive organisms (Salmonella, Shigella, Campylobacter)
- Pseudomembranous colitis associated with broad-spectrum antibiotics
Cautions
- Cardiac adverse reactions incl. QT prolongation, torsades de pointes, sudden death — avoid above-recommended doses, QT-prolonging drugs, QT risk factors
- Dehydration — fluid and electrolyte replacement
- GI disorders — stop if constipation, abdominal distention or ileus; toxic megacolon in AIDS patients
- Variability in pediatric response
Adverse reactions
- Constipation
- Nausea
- Abdominal cramps
- Dizziness
Pregnancy Category C — no teratogenicity in rat/rabbit studies; no adequate human studies; use only if benefit justifies risk
Lactation Small amounts may appear in breast milk; not recommended during breast-feeding
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 1 mg | cap | per unit | not offered | |
| 2 mg | cap | per unit | $0.05/ea | offered |
Generic entry1991
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Memory aids: interaction avatars
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Self-check
- Why does loperamide lack CNS opioid effects at normal doses?
P-glycoprotein keeps it out of the CNS. - What lethal cardiac risk occurs with massive loperamide abuse?
Torsades.