Major Uses

Cimetidine is in a drug class known as anti-ulcers. It is used for the treatment of gastric ulcers, stomach inflammation, and acid reflux in dogs, cats, horses, and other species. The drug decreases acid secretion in the stomach by blocking histamine receptors, which then provides a more satisfactory stomach pH. Cimetidine is also sometimes used in the treatment of mast cell tumors because these can produce large amounts of histamine.

Common Precautions

Very few side effects are seen in animals with the use of cimetidine when given at the recommended doses. However, the pet's veterinarian should be contacted if anything unusual occurs. Cimetidine should be used with extreme caution in patients with liver or kidney impairments. The drug is eliminated from the body by these organs and, if they are not working properly, then accumulation may occur. Cimetidine should be used carefully in geriatric animals, and also those with blood abnormalities. Possible drug interactions may occur, which can cause a reduction in the ability for the animal to remove the other drugs properly. Some examples of drugs that may interact with cimetidine are antacids, metronidazole, ketoconazole, and diazepam. The prescribing veterinarian should be informed of all other medications the pet is taking prior to administration cimetidine.

Cimetidine should not be administered to animals with a known allergy or hypersensitivity to the drug. Signs of an overdose may include tachycardia and respiratory failure. The pet's veterinarian, or an emergency veterinary clinic, should be contacted if these, or any unusual reactions occur.


Cimetidine should be stored at room temperature in tight, light-resistant containers. Since precipitation may occur if the injectable form is refrigerated, it should also be kept at room temperature.


Cimetidine is found in 100 mg, 150 mg, 200 mg, and 300 mg tablets. It is also available in 300 mg per 5 mL liquid, and also in the injectable form of a 150 mg/mL concentration. The typical dosage for dogs and cats is 3 - 5 mg/lb (5 - 10 mg/kg) by mouth every six to eight hours. For horses, typical administration is 300 - 600 mg four times a day by mouth, IV, or IM. 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 administered as soon as possible. However, if it is almost time for the next dose, the missed dose should be skipped and the regular dosing schedule should continue. Two doses should never be given at once.

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.