INFORMATION LIBRARY

What Is Loperamide?

Loperamide (brand names: Imodium A-D, Difixn) is a medicine classified as an opioid antidiarrheal. It is used in dogs and cats to treat loose stool and diarrhea that is not linked to infection in the stomach or intestines.

Its use in cats is controversial and should be done with extreme caution. Loperamide may also be used in dogs to prevent and treat diarrhea caused by cancer chemotherapy.

All uses in pets are considered “off-label” or “extra-label”, meaning they are not officially FDA-approved for animals but may still be safely recommended by veterinarians.

Important Notes

• The product Difixn is labeled for dogs but is not FDA-approved.
• Human product (Imodium A-D) is FDA-approved for humans but used extra-label in pets.
• Available in tablet, capsule, and liquid forms (OTC).
• Some human products contain additional ingredients (like simethicone) that are not safe for pets.

How Is Loperamide Used in Pets?

Loperamide is given orally up to three times daily, as directed by a veterinarian. The dosage for pets is different from human dosing.

• Can be given with or without food
• If stomach upset occurs, give with food
• Shake liquid forms before use
• Use proper measuring tools (dropper or syringe)
• Give slowly to ensure full dose intake

Benefits of Loperamide

• Available over the counter
• Fast-acting (works within 1–2 hours)
• Effective for non-infectious diarrhea

Monitoring & Follow-Up

Monitor your pet for improvement and any side effects. Contact your veterinarian if symptoms worsen.

• Fecal tests may be required
• Fluids and electrolyte levels may need monitoring

Warnings

• Do not use in pets allergic to loperamide
• Do not use in intestinal blockage
• Do not use for infection-related diarrhea
• Do not use in dogs with MDR1 gene mutation

Use With Caution

• Breathing problems
• Brain conditions or sedation issues
• Low thyroid or blood pressure
• Liver disease
• Pregnant or nursing animals

Side Effects

In Dogs:

• Drooling
• Constipation
• Bloating
• Sleepiness

In Cats:

• Similar effects as dogs
• Possible aggression or excitement

Drug Interactions

Loperamide may interact with other medications. Inform your veterinarian if your pet is taking:

• CYP-metabolized drugs
• P-glycoprotein (Pgp) drugs
• QT-prolonging medications

Safety for Pet Owners

• Keep out of reach of children
• Wash hands after handling
• Avoid if allergic

Overdose & Missed Dose

• Overdose can be serious—contact a vet immediately
• Do not double doses if one is missed

Storage

Store at room temperature and protect from light.