Though there are some known side effects of silybin, such as itching, gastrointestinal distress, and headaches- these side effects have only been observed in primates. When administered to dogs, on the other hand, the ingredient seems to be completely safe.
The ingredient is so safe, in fact, that the particular silybin-phosphatidylcholine complex used in Denamarin has been shown to have no adverse effects with concentrations of the compound up to 80 times greater than the amount included in Denamarin.
SAM-e has also been tested rigorously in both cats and dogs and has been shown to have no ill effects when administered in the concentration used in Denamarin. This means that neither ingredient in Denamarin should be capable of harming your dog, even when taken with other supplements recommended for liver support.
In fact, Nutramax Labs produces additional supplements that are ideal for use with Denamarin.
These supplements, Denosyl and Marin, include similar ingredients to Denamarin with additional nutrition and nuanced changes in its concentration of key ingredients like Silybin or SAM-e. These supplements can all be taken by your pet together, under the direction of your veterinarian, to provide comprehensive liver support.