Imodium (Loperamide) Dosing for Acute Diarrhea
Start with 4 mg immediately, then take 2 mg after each unformed stool or every 2-4 hours, never exceeding 16 mg in 24 hours. 1, 2, 3
Initial Dosing Strategy
- Take 4 mg (two capsules) as a loading dose immediately when acute non-bloody diarrhea begins 1, 2, 3
- Follow with 2 mg (one capsule) after each loose/unformed stool 1, 2, 3
- Alternatively, if the "after each stool" approach is impractical, take 2 mg every 2-4 hours to maintain consistent therapeutic effect 1, 2
- Never exceed 16 mg (eight capsules) in any 24-hour period due to serious cardiac risks including QT prolongation and potentially fatal Torsades de Pointes 1, 2, 3
Timeline and What to Expect
- Loperamide takes 1-2 hours to reach therapeutic effect, so space additional doses accordingly to avoid rebound constipation 1, 2
- Clinical improvement typically occurs within 48 hours 1, 3
- If no improvement after 48 hours, stop loperamide and seek medical evaluation for infectious causes or complications 1, 2
Essential Supportive Measures to Take Simultaneously
- Drink at least 1 liter of isotonic fluids daily to prevent dehydration 1
- Immediately eliminate lactose-containing products, coffee, alcohol, and spicy foods from your diet 1, 2
- Record stool frequency and watch for warning signs: fever, dizziness when standing, or bloody stools 1
When NOT to Use Imodium (Seek Medical Care Instead)
Do not take loperamide if you have any of the following—go to the hospital instead: 1, 2
- Fever with diarrhea
- Moderate-to-severe abdominal pain
- Bloody stools or black tarry stools
- Signs of dehydration (severe dizziness, decreased urination, extreme thirst)
- Severe immunotherapy-induced diarrhea (if you're on cancer immunotherapy)
These conditions require IV fluids and medical evaluation, not self-treatment with loperamide 1, 2
Critical Pitfalls to Avoid
- Don't delay starting loperamide—early intervention prevents progression to severe, complicated diarrhea requiring hospitalization 1, 2
- Don't exceed 16 mg daily under any circumstances—serious cardiac events including fatal arrhythmias can occur at higher doses 1, 2, 3
- Don't confuse overflow diarrhea from severe constipation (especially in elderly patients) with true diarrhea, as loperamide will worsen this condition 1
- Don't use loperamide if you suspect colitis or severe inflammatory bowel disease, as it may precipitate toxic megacolon 1, 2
If Diarrhea Persists Beyond 48 Hours
Medical evaluation is necessary to rule out infectious causes (C. difficile, Salmonella, E. coli, Campylobacter) 4. Your physician may add codeine 30 mg twice daily or consider other prescription treatments like octreotide with empiric antibiotics for refractory cases 1, 4.