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Home > Ask A Vet > Can You Give Dogs Imodium? Our Vet Explains

Can You Give Dogs Imodium? Our Vet Explains

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Dr. Maria Zayas

Veterinarian, DVM

The information is current and up-to-date in accordance with the latest veterinarian research.

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The short answer to whether you can give a dog Imodium is yes, technically, but not always. There is nuance to choosing when and how to treat canine diarrhea. At the risk of running my mouth about runny stool, we have everything you need to know about why Imodium isn’t commonly used in veterinary medicine and isn’t safe to give at home without veterinary supervision.


What Is Imodium?

Imodium, generic name loperamide, is a human anti-diarrheal medication. It is a synthetic opioid, but unlike most other opioids, it doesn’t affect the central nervous system and has therefore not been a controlled substance since the 1980s.

A little-known side effect of opioids is that they can cause constipation, which is how Imodium comes to be an anti-diarrheal medication. The intestinal tract moves food or digesta from the stomach to the rectum through peristalsis, which is involuntary but coordinated contractions of the muscles of the intestinal walls, pushing the digesta forward in a wave-like movement.

In dogs, we’ll refer to the rate of this movement as GI motility. Imodium slows this motility. The longer the digesta sits in the intestines and colon, the more water is pulled out, leading to firmer and less frequent stools. Diarrhea, by definition, is more frequent and liquid stools, so medications that lower GI motility, such as Imodium, work as an anti-diarrheal.

woman offering tablet to dog
Image By: ALPA PROD, Shutterstock

What Are the Risks of Using Imodium in Dogs?

This may sound counterintuitive, but not all diarrhea is bad. It serves an important purpose, like any other bodily function. In dogs, an infectious agent is involved in most cases of diarrhea that wouldn’t resolve on their own within a day or so. This means things like bacteria or viruses that cause diarrhea. Toxins can be another example that isn’t infectious but relies on diarrhea for treatment. In all these cases, diarrhea is part of expelling these things from the GI tract, where accumulation can cause inflammation, worsening infection, and even sepsis.

If Imodium is given at home without identifying the cause of diarrhea, there is a risk of masking signs of illness and not treating something that absolutely needs direct treatment.

Giving Imodium is also not safe for all dogs. There is a known mutation in many dogs, especially in certain breeds such as Collies and Australian Shepherds, known as the MDR1 gene mutation, which keeps these dogs from metabolizing certain medications, such as Imodium. This allows the medication to build up in their body and can cause toxicity, which will look like severe sedation.

Imodium should also be used with caution or avoided in dogs with the following:
  • Hypothyroidism
  • Addison’s
  • Head injuries
  • Bowel perforation
  • Respiratory dysfunction or distress
  • Hepatic encephalopathy
  • Liver disease

What Are the Side Effects of Using Imodium in Dogs?

Sad tired beagle dog on sofa. Sick dog.
Image By: ALEX_UGALEK, Shutterstock

While usually mild, these are the most common side effects of Imodium use in dogs:

  • Constipation
  • Salivation (drooling)
  • Bloat
  • Sedation

More severe but less common side effects can include:

  • Profound sedation (especially in dogs with the MDR1 gene mutation)
  • Debilitating lack of GI motility
  • Pancreatitis
  • Wobbling/ataxia
  • Dilated pupils

divider-dog paw

What Can Imodium Be Used for in Dogs?

Imodium is rarely recommended as an over-the-counter medication in dogs. It’s most likely use is for chemotherapy patients to relieve diarrhea associated with their medications. This would be prescribed by a veterinarian for this specific purpose and carefully dosed to avoid side effects.

In some cases, Imodium may also be used for diarrhea in dogs that are going to see a veterinarian but need to make it through the night or a weekend until their vet opens. This should also always be evaluated and dosed by a veterinarian first to assess the risk of masking important signs needed to find the cause of the diarrhea.

sad and sick labrador retriever dog
Image By: My July, Shutterstock

What Can’t Imodium Be Used for in Dogs?

Diarrhea caused by an infectious agent or a toxin, as explained above, should not be treated with Imodium as this can be dangerous. Diarrhea caused by a foreign body object should also not be treated with Imodium, as this can worsen an obstruction and is dangerous if a perforation of the intestinal wall has occurred.

Parasitic diarrheas, such as those from worms, coccidia, or giardia, should also not be treated by Imodium.

Diarrheas resulting from stressors or food changes will resolve themselves in most cases, and when they don’t, they usually need antibiotics to correct something known as bacterial overgrowth, so Imodium should not be given in these cases as it can hide signs of bacterial overgrowth and delay proper treatment.

What Else Can I Do for Diarrhea in My Dog?

The better choice for home care for diarrhea is to change a dog’s diet to a bland diet until they can be seen by a veterinarian. This is classically a mix of plain chicken and rice, possibly with pumpkin, but there are alternative recipes for animals with restrictive food allergies.

Giving probiotics is also recommended for any dog that experiences diarrhea. Increasing both water intake and exercise frequency can help these dogs stay comfortable too.



While Imodium can technically be given in dogs, it is rarely a good choice for diarrhea and presents several risks, despite being an over-the-counter medication. If Imodium is going to be given, it should be prescribed and dosed by a veterinarian who has screened if it is an appropriate time to use the medication. Dogs with the MDR1 gene mutation should avoid using Imodium more than most, as should dogs ill with several other conditions.

Featured Image Credit: Creative Cat Studio, Shutterstock

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