What is the proper dosage of Imodium (Loperamide) to administer?

How to Administer Imodium (Loperamide)

Start with 4 mg (two capsules) initially, then give 2 mg (one capsule) after each unformed stool, not exceeding 16 mg (eight capsules) per day. 1

Standard Dosing for Adults and Adolescents ≥13 Years

• Initial dose: 4 mg (two capsules) as a loading dose 2, 1
• Maintenance: 2 mg after each unformed stool 2, 1
• Maximum daily dose: 16 mg (eight capsules) in 24 hours 2, 1
• Timing consideration: Wait 1-2 hours between doses since loperamide takes this long to reach therapeutic effect, preventing rebound constipation 3

The FDA label and multiple international guidelines (ESMO, International Society for Travel Medicine) consistently recommend this dosing strategy, making it the gold standard approach. 2, 1

Pediatric Dosing (Ages 2-12 Years)

Loperamide is contraindicated in children under 2 years due to respiratory depression and cardiac risks. 1

First Day Dosing:

• Ages 2-5 years (13-20 kg): 1 mg three times daily (3 mg total) - use liquid formulation 1
• Ages 6-8 years (20-30 kg): 2 mg twice daily (4 mg total) 1
• Ages 8-12 years (>30 kg): 2 mg three times daily (6 mg total) 1

Subsequent Days:

• Give 1 mg per 10 kg body weight only after each loose stool 1
• Do not exceed first-day maximum dosages 1

Clinical Context Matters

Uncomplicated Diarrhea (Grade 1-2):

• Use standard dosing as above 2
• Combine with oral hydration and dietary modifications (eliminate lactose, high-osmolar supplements, coffee, alcohol, spices) 2
• Instruct patients to record stool frequency and report warning signs (fever, dizziness on standing) 2, 3
• Clinical improvement typically occurs within 48 hours 1

Complicated Diarrhea (with fever, dehydration, severe cramping, or bloody stools):

• Same loperamide dosing can be used (4 mg initially, then 2 mg after each loose stool, max 16 mg/day) 2
• However, hospitalization is required with IV fluids, antibiotics (fluoroquinolones), and possibly octreotide 2
• Obtain stool studies and complete blood count 2
• Avoid loperamide if bloody diarrhea or dysentery is present without antibiotic coverage 4

Important Safety Warnings

Never exceed 16 mg per day - higher doses risk serious cardiac adverse reactions including QT prolongation and Torsades de Pointes. 1

Absolute Contraindications:

• Children under 2 years of age 1
• Bloody diarrhea or suspected invasive bacterial infection without antibiotics 3, 4
• Neutropenic enterocolitis (anticholinergics and antidiarrheals worsen ileus) 4
• Grade 3-4 immunotherapy-induced diarrhea 2, 4

Use with Caution:

• Elderly patients taking QT-prolonging drugs (Class IA or III antiarrhythmics) 1
• Hepatic impairment (reduced metabolism increases systemic exposure) 1
• If symptoms worsen or persist beyond 48-72 hours, discontinue and reassess 3

Chronic Diarrhea Management

• Start with same initial dosing (4 mg, then 2 mg after each unformed stool) 1
• Once controlled, reduce to lowest effective maintenance dose (typically 4-8 mg daily) 1
• Can be given as single daily dose or divided doses 1
• If no improvement after 10 days at 16 mg/day, further loperamide is unlikely to help 1
• Has been used safely for up to 3 years without tolerance 5

Combination Therapy

• With antibiotics: For moderate-severe traveler's diarrhea, loperamide plus antibiotics increases cure rates compared to either alone 3
• With oral rehydration: Adding ORT to loperamide offers no additional benefit when patients drink fluids ad libitum 6
• With simethicone: The combination provides faster relief of gas-related abdominal discomfort than loperamide alone 7

Special Populations

• Elderly: No dose adjustment needed, but increased susceptibility to QT effects requires caution with interacting medications 1
• Renal impairment: No dose adjustment required (drug excreted in feces) 1
• Hepatic impairment: Use with caution due to increased systemic exposure 1