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Loperamide

Opioid antidiarrheal (mu-receptor agonist, peripherally acting)

Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team

Species

Dog

Brands

3 available

Interactions

1 documented

Formulations

Mechanism of action

Activates mu-opioid receptors in the GI tract, slowing intestinal motility and enhancing water and electrolyte absorption; does not cross BBB at therapeutic doses (except in MDR1 mutant dogs)

At a glance

Class

Opioid antidiarrheal (mu-receptor agonist, peripherally acting)

Schedule

OTC

Storage

Store below 25°C

Dosing

🐕

Dog

Acute non-infectious diarrhoea

Dose

0.08–0.2 mg/kg

Route

Frequency

BID to TID

Max dose

8 mg/dose; 24 mg/day

Duration: Short-term only (1–3 days); identify and treat underlying cause

Educational reference only

This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Capsule — 1

Strength

2mg

Available in India

🧴

Oral solution — 1

Strength

0.2mg/mL

Available in India

Storage

Store below 25°C

Safety

Absolute contraindications — do not use

MDR1 (ABCB1) mutation carriers
Can cause severe neurotoxicity (CNS depression, coma)
CollieAustralian ShepherdShetland SheepdogOld English SheepdogBorder Collie
Cats (not recommended)
Excitatory CNS effects in cats
Infectious diarrhoea
May worsen by retaining toxins/organisms

Adverse effects

Common

Constipation

Bloating

Serious

CNS depression in MDR1 mutants

Ileus

Pancreatitis

Monitoring parameters

Stool consistencyMDR1 genetic status (herding breeds)Neurological signs

Educational reference only

Interactions

Major — 1

Ivermectin

major

Both are P-glycoprotein substrates; MDR1-mutant dogs cannot efflux either drug, causing fatal CNS toxicity

Management: Avoid loperamide in MDR1-mutant breeds (Collies, Shelties, Aussies). Test MDR1 status before use.

Educational reference only

Brands

International

Imodium

Johnson & Johnson

India

Eldoper

Elder Pharma

Lopamide

Cipla

FAQs

Frequently asked questions

›What is Loperamide?

Loperamide is a opioid antidiarrheal (mu-receptor agonist, peripherally acting) used in pets. Activates mu-opioid receptors in the GI tract, slowing intestinal motility and enhancing water and electrolyte absorption; does not cross BBB at therapeutic doses (except in MDR1 mutant dogs)

›What is Loperamide used for in pets?

Loperamide is used in veterinary medicine for: Acute non-infectious diarrhoea.

›What is the Loperamide dose for dogs?

For dogs, Loperamide is typically dosed as follows — Acute non-infectious diarrhoea: 0.08–0.2 mg/kg PO BID to TID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What are the side effects of Loperamide?

Common: Constipation, Bloating. Serious (call your vet immediately): CNS depression in MDR1 mutants, Ileus, Pancreatitis.

›Does Loperamide need a prescription?

Loperamide is available over the counter. Even so, you should consult your veterinarian before giving any medication to your pet.

›When should Loperamide not be used?

Do not use Loperamide if: MDR1 (ABCB1) mutation carriers; Cats (not recommended); Infectious diarrhoea.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database