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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
2

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
PO
Frequency
BID to TID
Max dose
8 mg/dose; 24 mg/day
Duration: Short-term only (1–3 days); identify and treat underlying cause

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

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.

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.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
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 →