Major Uses

Bismuth subsalicylate is an antidiarrheal used to treat stomach problems, such as stomach inflammation, indigestion, vomiting, and of course, diarrhea. The drug works by soothing the lining of the intestines and stomach. It can also be prescribed as part of a multi-drug therapy, commonly known as "triple therapy," to treat infections caused by a gastrointestinal bacteria called Helicobacter, which is a common cause of ulcers and stomach inflammation.

The drug is mainly prescribed for dogs and sometimes horses. Bismuth subsalicylate is very rarely prescribed to cats because of their sensitivity to aspirin; veterinarian supervision is strongly recommended.

Common Precautions

Bismuth subsalicylate is a typically safe and effective drug, however, adverse reactions are possible. The most common side effect seen after the drug is administered is darkening of the pet's stool to a gray-black or green color. Sometimes this can be confused with melena (blood in the stool). Some animals may experience constipation as well. Bismuth subsalicylate should be used with caution, or not at all, in patients who have bleeding conditions, or are pregnant or lactating. As mentioned above, salicylates should be used with extreme caution in cats as it can be fatal.

Because possible drug interactions can occur, the pet's veterinarian should be aware of all other medications the pet is taking before bismuth subsalicylate is prescribed. Because of the salicylate component, the drug should not be taken with aspirin. Bismuth subsalicylate can decrease the effects of tetracycline products, and it is recommended that administration of the two drugs be separated by two hours.

Bismuth subsalicylate should not be administered to animals with a known allergy or hypersensitivity to the drug or other aspirin products. The pet's veterinarian should be contacted if the patient has a fever, shows signs of abdominal pain, or acts depressed or inactive. If the symptoms the drug is supposed to treat persist for more than 48 hours, the prescribing veterinarian needs to be contacted; alternate methods of treatment may be necessary.


Bismuth subsalicylate should be stored in a light resistant and childproof container. It should be stored at room temperature, unless the manufacturer storage instructions state otherwise.


The drug is found in oral suspension, paste, chewable tablet, and caplet form. Oral suspensions should be shaken well prior to administration, and it has been found that refrigerating the liquid can make it more palatable for some animals. A typical dose for dogs is 0.5-1.5 mL/lb (1-3 mL/kg) per day, typically divided between two to four doses over 24 hours. For horses, the typical dose is 3-4 ounces per 45 kg of body weight three to four times a day. Typical dosing for cats is 0.125 mL/lb (0.25 mL/kg) every 4-6 hours. Cats should not receive frequent or high doses since it can be toxic. Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose is missed it should be given as soon as possible, unless it is almost time for the next dose. The dose should not be doubled, so the missed dose is to be skipped and the regular dosing schedule continued. The prescribing veterinarian should be contacted if there are any questions.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.