Denamarin Side Effects

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Denamarin is available in tablet and chewable form.
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Denamarin is a liver supplement for dogs that contains silybin and S-Adenosylmethionine, more commonly known as SAMe. Denamarin is available only by prescription by a veterinarian. Denamarin is safe for dogs, but contact your vet immediately if you see any changes in behavior or appearance.


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Liver and Brain Support

The active ingredients in Denamarin support liver and brain health. The SAMe helps prevent the death of liver cells and encourages liver cell regeneration and repair. It also helps brain health by maintaining SAMe levels in the fluid surrounding the brain. Silybin is the active ingredient in milk thistle extract. It helps the body maintain a healthy oxidative balance, which supports and protects both the brain and the liver.


Potential Side Effects

The ingredients in Denamarin are safe for dogs. Potential side effects of silybin includes headaches, gastrointestinal problems and itching. However, in clinical trails these symptoms were observed only in primates. According to, dogs showed no ill effects, even when given a dosage 80 times higher than the amount in Denamarin for a period of 26 weeks. VCA Animal Hospitals states that mild digestive upset may occur in dogs taking milk thistle, the herb containing silybin.


SAMe also has low toxicity in dogs. SAMe side effects are rare and limited to mild gastrointestinal irritation and nausea, according to the VCA Animal Hospitals website. SAMe, which can heighten moods, may not be suitable for highly excitable dogs.

Silybin and Cancer

Silybin found in milk thistle has been shown to help reduce the side effects of cancer treatments, but it requires caution. One study demonstrated that high doses of milk thistle increased the toxicity of chemotherapy, according to "Veterinary Practice News". Researchers also have concerns that, while the silybin helps stimulate liver regeneration, it may also stimulate growth of liver tumors, although research is not conclusive.


Additional Supplements

Vets may recommend that dogs who need additional liver support take the supplement Marin along with Denamarin. Marin provides an additional dose of silybin as well as vitamin E and zinc. The formula is designed to increase the bio-availability of silybin compared to that of milk thistle supplements.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.