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PetDosageChart

Imodium (Loperamide) Dosage for Dogs

Antidiarrheal opioid agonist ⏱ Onset: 1-2 hours ⏳ Duration: 8-12 hours

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. This information is sourced from veterinary drug references including Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

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Imodium Dosage Chart for Dogs by Weight

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Weight Low Dose Standard Dose Max Dose Frequency
5 lbs (2.3 kg) 0mg 0.5mg 0.5mg Every 8-12 hours
10 lbs (4.5 kg) 0.5mg 0.5mg 1mg Every 8-12 hours
15 lbs (6.8 kg) 0.5mg 1mg 1.5mg (2mg tablet) Every 8-12 hours
20 lbs (9.1 kg) 1mg 1.5mg (2mg tablet) 2mg (2mg tablet) Every 8-12 hours
25 lbs (11.3 kg) 1mg 1.5mg (2mg tablet) 2.5mg Every 8-12 hours
30 lbs (13.6 kg) 1.5mg (2mg tablet) 2mg (2mg tablet) 2.5mg Every 8-12 hours
40 lbs (18.1 kg) 2mg (2mg tablet) 2.5mg 3.5mg (2 × 2mg) Every 8-12 hours
50 lbs (22.7 kg) 2.5mg 3.5mg (2 × 2mg) 4.5mg Every 8-12 hours
60 lbs (27.2 kg) 2.5mg 4mg (2 × 2mg) 5.5mg (3 × 2mg) Every 8-12 hours
70 lbs (31.7 kg) 3mg 5mg 6.5mg Every 8-12 hours
80 lbs (36.3 kg) 3.5mg (2 × 2mg) 5.5mg (3 × 2mg) 7.5mg (4 × 2mg) Every 8-12 hours
90 lbs (40.8 kg) 4mg (2 × 2mg) 6mg (3 × 2mg) 8mg (4 × 2mg) Every 8-12 hours
100 lbs (45.4 kg) 4.5mg 7mg 9mg Every 8-12 hours
120 lbs (54.4 kg) 5.5mg (3 × 2mg) 8mg (4 × 2mg) 11mg Every 8-12 hours
150 lbs (68 kg) 7mg 10mg (5 × 2mg) 13.5mg (7 × 2mg) Every 8-12 hours

What is Imodium (Loperamide) used for in dogs?

Acute diarrhea Chronic diarrhea Inflammatory bowel disease-related diarrhea

How to give Imodium to your dog

Give loperamide by mouth. Tablets can be given with or without food. If using liquid formulation, measure carefully with a syringe. CRITICAL: Do NOT give to Collies, Australian Shepherds, Shetland Sheepdogs, or any herding breed mix without MDR1 genetic testing — loperamide can cause fatal neurotoxicity in MDR1-mutant dogs. Use only plain loperamide products (no multi-symptom formulas). Limit use to 2-3 days unless directed otherwise by your vet.

Available Forms

Tablet, Capsule, Liquid

Give with Food?

No — can be given without food

Side effects of Imodium in dogs

Common side effects

Constipation
Bloating
Sedation
Gas

Serious side effects

  • CNS depression in MDR1-mutant breeds
  • Severe constipation
  • Pancreatitis
  • Toxic megacolon
  • Respiratory depression

When to call the vet

Call your vet immediately if your dog shows any of these signs:

  • Severe sedation, stumbling, or disorientation (especially in herding breeds)
  • Diarrhea persists beyond 48 hours despite treatment
  • Bloody stool or vomiting develops
  • Abdominal distension or signs of pain
  • No bowel movements for more than 48 hours after starting treatment

Related Medications for Dogs

Antidiarrheal / Gastroprotectant

Pepto Bismol

Bismuth Subsalicylate

For diarrhea

View dosage chart
Opioid analgesic

Ultram

Tramadol

For moderate to severe pain

View dosage chart
Antihistamine

Benadryl

Diphenhydramine

For allergies

View dosage chart
Serotonin antagonist and reuptake inhibitor (SARI)

Desyrel

Trazodone

For anxiety

View dosage chart

Sources & References

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Loperamide.

Frequently Asked Questions

Why is loperamide dangerous for Collies and related breeds?
Dogs with the MDR1 (ABCB1) gene mutation lack functional P-glycoprotein at the blood-brain barrier. Loperamide, which normally stays out of the brain, can cross into the CNS in these dogs, causing severe neurological toxicity including sedation, disorientation, tremors, and potentially death. Affected breeds include Collies, Australian Shepherds, Shetland Sheepdogs, and mixes of these breeds.
Can I give my dog Imodium from the pharmacy?
Plain loperamide (Imodium A-D) tablets or liquid may be used, but NEVER use Imodium Multi-Symptom Relief as it contains simethicone or other ingredients. Always confirm the product contains only loperamide. Consult your vet before giving any over-the-counter medication.
How long should I give loperamide to my dog?
Loperamide should typically be used for only 2-3 days for acute diarrhea. If diarrhea persists beyond this, veterinary evaluation is needed to determine the underlying cause. Prolonged use without diagnosis can mask serious conditions.
Should I test my dog for the MDR1 mutation before giving loperamide?
Yes, if your dog is a herding breed or mixed breed of unknown heritage, MDR1 genetic testing is strongly recommended before administering loperamide. Testing is available through veterinary genetics labs and can be done with a simple cheek swab.
When should I NOT give loperamide for diarrhea?
Do not give loperamide if your dog has bloody diarrhea, fever, vomiting, suspected infection, or has ingested toxins. In these cases, diarrhea may be the body's way of expelling harmful agents, and stopping it can worsen the condition. Always see a vet for diarrhea lasting more than 24-48 hours.

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