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Cimetidine’s Anti-Cancer Effects in Dogs

Recently, Tripawds member Tai brought it to our attention that Cimetidine, an over-the-counter heartburn medication for humans (also known as Tagamet), has been found to prevent cancer metastis in dogs with mast cell tumors. Several reputable studies have confirmed this.
Tagamet Acid Reducer, 200 mg, 30 tablets
Cimetidine is often given to Tripawds to help with nausea after chemotherapy, or to prevent gastric ulcers when switching medications, such as NSAIDs. If your vet has prescribed an acid-reducers to help with nausea, such as Prilosec, be sure to ask if it’s OK to give Tagamet instead. According to,

Cimetidine is often used to treat and prevent ulcer formations in the pet’s intestine and stomach. It works to adjust the pH balance in the stomach by blocking the histamine-2 receptor.

Cimetidine is also known as histamine a2 antagonist, as it reduces acid formation in the stomach. Although it may not be beneficial to pets with high grade cancer, it can help to reduce the effects of mast cells on the gastrointestinal tract.

Dr. Demian Dressler, author of the Dog Cancer Survival Guide, has also added Cimetidne to his list of mast cell tumor treatments, and Tai posted information about several studies which discuss this drug’s anti-cancer effects. Another study by Life Extension Foundation, says:

“Cimetidine works through several mechanisms of action, preventing immune suppression caused by tumor secretion of histamine, halting cancer growth, preventing angiogenesis, promoting cancer cell death, and averting often-fatal cancer metastasis.”

Cimetidine is also known by the brand names of  Tagamet, and is in the same family of drugs as Famitidine, Ranitidine and Zantac. Ask your vet for details about whether it’s right for your Tripawd.

6 Responses to “Cimetidine’s Anti-Cancer Effects in Dogs”

  1. My dog has prostate and bladder cancer. Is there any evidence Cimetidine is effective on slowing this form of cancer?

  2. Good question! We suggest you ask in the discussion forums since we don’t know. Best wishes.

  3. I read about this about 4-5 months months ago. Very interesting…Charley has been taken generic pepcid (famotidine) 2x/day the past 2 years because he was a puker. If it’s an added bonus to cancer that’s even better news!
    Ellen & Charley

  4. 2 of my boxers recently were diagnosed with mast cell tumors. Neither tumor was operable (one inside the ear of my 12 year old dog who was having seizures, the other the entire upper eyelid of my 13 year old boxer). Both were started on diphenhydramine at 4 mg/kg, twice daily; cimetidine 4 mg/kg, three times daily. My 12 year old female, Gretakins, was immediately started on oral prednisone at 2 mg/kg, twice daily. In 14 days her visible tumor was gone, as were her vomiting, diarrhea, seizures, and neurological issues (seizures, high stepping, decreased eyesight). My 13 yr old’s (King Gustav) eyelid returned to normal size within 7 days. Mast cell tumors were confirmed in both via fine needle aspirate. We went through a LOT of puppy pads, but both my babies are clear and healthy today. Gretakins is 1 yr out (she wasn’t expected to survive 30 days from diagnosis date). King Gustav is 6 months out from treatment start date. I’m a veterinary technician, and am overjoyed that my rescue babies have done so well after such a sad diagnosis.

  5. Helen martyszyn June 28, 2017 at 7:07 am

    Just got the call…our dog has lymphoma

  6. @Helen Martyszyn My heart goes out to you. My girl had mast cell cancer and I had her on benadryl and tagamet for 15 months and she did great. She ended up getting hemangiosarcoma last summer and quickly declined, leaving me 4th of July 2016. 🙁 Prayers to your doggie. Miracles can happen.

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