CBD is a possible cause of loose stools or diarrhea in dogs, although it does not affect every dog this way. In one long-term dog study, dogs given 10 mg/kg of CBD oil had more soft feces and diarrhea than dogs given lower doses or placebo. Veterinary references also list vomiting, drooling, lethargy and unsteadiness as possible side effects.

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CBD and Dog Diarrhea at a Glance

Question Short answer
Can CBD cause diarrhea in dogs? Yes, it can.
Does timing prove that CBD caused the diarrhea? No. Diet changes, treats, infection, parasites, stress and other illnesses can cause diarrhea too.
What should you do? Do not give another non-prescribed dose until you speak with your veterinarian.
When is it urgent? Blood or black stool, repeated vomiting, weakness, severe diarrhea, tremors, seizures or suspected overdose need prompt veterinary advice.
Is CBD approved for dogs? The FDA has not approved cannabis or CBD products for any use in animals.

Why Can CBD Cause Diarrhea in Dogs?

CBD may contribute to diarrhea for several reasons:

  • Dose or concentration: One long-term dog study found more soft feces and diarrhea in dogs receiving 10 mg/kg of CBD oil than in dogs receiving lower doses or placebo. Other controlled studies reported few gastrointestinal side effects, so dogs do not all react the same way.
  • Product formulation: CBD oils, soft chews and broad-spectrum products contain different amounts of CBD and other ingredients. A dog may tolerate one product better than another.
  • Product quality: The FDA warns that some CBD products contain a different amount of CBD than the label states. Some may also contain contaminants, including THC.
  • Another cause: A new treat, sudden food change, rich food, stress, parasites, infection or gastrointestinal illness can cause diarrhea around the same time as CBD use. Timing alone does not show that CBD caused the problem.

CBD itself is considered non-intoxicating. Some products may contain THC or other cannabinoids, however. THC exposure is more often linked to lethargy, poor coordination, tremors, agitation or seizures, although vomiting and diarrhea can also occur after cannabis exposure.

What Should You Do if Your Dog Has Diarrhea After CBD?

  1. Do not give another dose of a non-prescribed CBD product until you have spoken with your veterinarian.
  2. Contact the prescribing veterinarian before changing treatment if your dog receives cannabidiol for seizures or another ongoing condition. VCA advises against suddenly stopping cannabidiol when it is being used for seizure control.
  3. Keep fresh water available and monitor your dog's energy, appetite, vomiting and stool.
  4. Save the product packaging. Write down the brand, CBD concentration, amount given, time of administration and any other medications or supplements.
  5. Do not give Pepto-Bismol, Imodium or another human anti-diarrhea medicine unless a veterinarian tells you to. These products may be unsafe or unsuitable for some dogs.

A single mild episode in an otherwise bright, comfortable adult dog may not be an emergency. Multiple watery stools, continuing diarrhea or any additional symptoms warrant veterinary advice. Diarrhea that does not improve within 48 hours should be assessed by a veterinarian.

Diarrhea after CBD needs urgent veterinary care when it occurs with:

  • Red blood or black, tarry stool
  • Repeated vomiting
  • Severe or profuse diarrhea
  • Weakness, collapse, marked lethargy or difficulty standing
  • Refusal to eat or drink
  • A painful or bloated abdomen
  • Tremors, seizures, severe incoordination or heavy drooling
  • A suspected overdose or ingestion of a CBD product containing THC

The FDA recommends contacting a veterinarian, emergency animal hospital or animal poison control center when a pet shows adverse effects after ingesting cannabis or a cannabis-containing product.

Bottom Line

Keep the product packaging and dosing details available when you call your veterinarian. They can help determine whether the diarrhea is linked to CBD, another ingredient or a separate health problem.