Dog's diarrhea

Loperamide ( e.g. Stoperan, Imodium) for people and dogs living the fast paced life

Loperamide is a kind of a synthetic opioid. At therapeutic doses, loperamide acts on opioid receptors in the intestines, without affecting the central nervous system. It slows down intestinal peristalsis and reduces the loss of water from the intestines, which in turn results in diarrhea diminishing.

Well tested scientifically loperamide is safe for human as long as we stick to therapeutic doses. But there is a list of contraindications for its use and I would strongly recommend to read the leaflet carefully.

Briefly, do not take it if:

– you have liver problems (your liver can metabolize it in a different harmful for you way)

– you suffer from antibiotic-associated diarrhea

– you notice some blood in your stool

– you have chronic problems with your guts

– you suspect E.Coli or Salmonella poisoning

For sure loperamide is not safe for children under 2 y. and can be toxic for babies (in US so far there have been 6 officially reported cases of death of children under 6 months, who were given loperamide).

There is also another problem observed with that drug. In 2016, the FDA (U.S Food and Drug Administration) issued a warning about a danger associated with loperamide overdose, which could result in serious heart problems.

It was also reminded that loperamide interacts with many drugs, including antimalarial medications, anti-viral and common taken anti-reflux drugs – (e.g. ranitidine), some antibiotics (erythromycin, clarithromycin) and others.

These drugs can cause loperamide absorption to increase. And a piece of advice from me – do not take any herbal infusions etc. during loperamide therapy.

On 30th of January 2018, the next FDA announcement was published informing that loperamide overdosing reports persist to flow from medical centers of US.

Loperamide for dog’s diarrhea

Looking for information of loperamide treatment in dogs, I came across relatively few specific sources. A study from 1974 (available only in an abstract) states that dogs given 5 mg of loperamide on 1 kg of body weight(mg/kg) felt good.

Another study found that dogs fed with loperamide for a whole year in dosage ranging from 0, 31 mg/kg to 5 mg/kg were doing great – apart from some depression and bloody diarrhea from time to time. In my opinion bloody diarrhea is not a sign of “doing great”.

It was not until 1996 that more extensive information appeared, French scientists analyzed 40 cases of loperamide poisoning in dogs. Most of the tested animals became ill after an episod of overdosing (the recommended dose at that time was 0.08 mg / loperamide per 1 kg of body weight).

Symptoms characteristic for opiate poisoning were observed: mydriasis, ataxia, abdominal cramps, vomiting, salivation, hypothermia, bradycardia and in more severe cases respiratory problems or even coma.

All dogs were saved with an antidote administration – in that case, it was naloxone. Dogs needed careful 24 hours medical monitoring afterward.

Some very interesting observation was made in that study. Dogs of Collie breed represented 1/3 of animals tested, in their case overdosing with loperamide was relatively small compared to other dogs but ending with the same symptoms of acute poisoning

A few years later, a genetic mutation in Collie and related breeds was described known now as the MDR1 mutation. That mutation enables some chemical compounds (loperamide including) to cross the blood-brain barrier leading to severe neurotoxic symptoms.

Today, it is known that apart from Collie some other breeds, among them: Whippets, Old English Sheepdogs, Swiss and Australian shepherds even the German ones, are susceptible to the MDR1 mutation.

While dangerous for animals with genetic mutation, what about “healthy”, not mutated dogs, is loperamide safe for them?

Yes, theoretically it is. But in my opinion the same contraidications as for people should be considered carefully especially that some of them were listed officially.

In 2007 The France National Veterinary Commision yielded a report titled ”Study in Adverse Reactions Observed After Loperamide Exposure”.

Although the report focused mainly on the description of poisoning due to genetic mutations, some precautions in loperamide use for all dogs were recommended.

Here it goes: liver disease, intestinal obstruction, hemorrhagic gastroenteritis, age under 3 months, weight under 2kg, pregnant or nursing animals. Additionally, calcium channel blockers and drugs affecting intestinal motility have not been recommended during treatment with loperamide.

In years 2000-2006, the American Animal Poison Control Center reported 862 cases of dog’s poisoning with loperamide. In years 2009-2013 – 766 cases. Be careful then.

Summary: the theoretical safe dose of loperamide for a dog differes from 0,08 to 0.1 mg / kg – twice daily. So for a 10 kg dog (some 5-pound dog ) you should give max. 1mg of loperamide as a single dose.

Considering that an ordinary pill usually contains 2 mg of loperamide, there may be a problem with precise dosing!

Contraindications one more time-

ABSOLUTE NO for Collie or related breed !!!!

Besides: do not give it to puppies or very tiny adult dogs and pregnant or nursing bitches. Stop treatment immediately if there is blood in the stool. In case of co-existing diseases of liver, kidneys, pancreas or thyroid gland. administer loperamide only under careful medical supervision. Do not mix with ranigast or other anti-reflux medicines (proton pump inhibitors). Do not mix with any herbs.

If any symptoms of poisoning occur immediately seek medical help.

*1 pound (lb) is equal to 0.45359237 kilograms





1Gulstad MB, et al. Ugeskr Laeger. 2015. Ischaemic colitis after loperamide treatment

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2 Mehran Howaizi , Mohammed Saïd Sbaï-Idrissi (, Patrice Baillet . Pancréatite aiguë secondaire à la prise de lopéramide Gastroentérologie Clinique et Biologique. Vol 24, N° 5  – juillet 2000 pp. 589-590Doi : GCB-05-2000-24-5-0399-8320-101019-ART21

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Accessed 22.03.18

4 FDA Drug Safety Communication: FDA warns about serious heart problems with high doses of the antidiarrheal medicine loperamide (Imodium), including from abuse and misuse .Dostępne na dzień 22.03.18 z :

5 FDA Drug Safety Communication: FDA limits packaging for anti-diarrhea medicine Loperamide (Imodium) to encourage safe use. Accessed 22.03.18 :

6 Marsboom, R., Herin, V., Verstraeten, A., Vandesteene, R., and Fransen, J.: Loperamide (R18 553), a novel type of antidi arrheal agent. Part 4: studies on subacute and chronic toxicity and the effect on reproductive processes in rats, dogs and rabbits. Arzneim.-Forsch. (Drug Research), 24:1645-1649, 1974.

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7 Product Monograph Pr Apo-Loperamide loperamide hydrochloride tablets USP 2 mg Oral Antidiarrheal Agent APOTEX INC. 150 Signet Drive Toronto, Ontario M9L 1T9 Date of revision: October 16, 2017

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8 LUDY E. C. VAN BEIJSTERVELDT, RITA J. F. GEERTS, KOEN WUYTS,ROBERT J. H. WOESTENBORGHS, WILLEM E. G. MEULDERMANS,AND JOSEPH J. P. HEYKAN Gastrointestnal distribution of the prodrug Loperamide oxide and its active drug loperamide in the dog. Department of Drug Metabolism and Pharmacokinetics, Janssen Research Foundation. Copyright C 1995 by The American Society for PharmacologyAnd Experimental Therapeutics 090-9556/95/2302-0216$02.00/O

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9 Hugnet C, Cadore JL, Buronfosse F, Pineau X, Mathet T, Berny PJ Loperamide poisoning in the dog. Vet Hum Toxicol. 1996. Accessed 22.03.18 : (Full-text (PDF)Available from: Philippe Berny, Apr 30, 2015 )

10 Etude des effets indésirables observés après exposition au lopéramide



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11 Lotfi El Bahri .Loperamide – investigating a human medication toxic to pets.

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12 Jennifer Coates, DVM Imodium for Dogs: Is it a Good Idea?

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