Is it safe to give my cat milk thistle and in what form?

Milk thistle (Silybum marianum) is an herb used to heal liver cells, protect the liver from hepatic disease and detoxify it after chemotherapy or any drug (such as flea medication) that is causing side effects. It contains silymarin, a flavonoid compound known to have healing properties in the liver, but herbalists recommend using the whole herb rather than isolated silymarin, as other compounds in milk thistle unknown to science may benefit the cat. Check with an experienced herbalist or naturopathic veterinarian before giving milk thistle to your cat.
Silymarin reaches high levels in the bile and liver (it also reaches significant levels in the lungs, pancreas, prostate, and skin). It can be used in the treatment of feline hepatic lipidosis, chronic hepatitis, cholangitis (inflammation of the bile ducts), and pericholangitis (inflammation of the tissue around the bile ducts). It may be useful in preventing or treating gallstones by thinning the bile.
Many cats and dogs with inflammatory bowel disease (IBD) have concurrent inflammation of the liver/bile system and the pancreas. This threesome of symptoms is called “triaditis.” Because milk thistle’s beneficial actions concentrate on the liver and bile systems, it may also be helpful in animals with IBD.
Milk thistle generally supports the immune system through its powerful antioxidant, free-radical scavenging action, its ability to preserve the supply of another important antioxidant, glutathione, as well as direct effects on immune cells. Glutathione, which is stored primarily in the liver, naturally declines over time, and depletion of this protein appears to accelerate the aging process.
Milk thistle is available in tincture or pill.
NOTE: Cats suffering from acute liver damage may require much higher doses of milk thistle than a cat with mild liver damage, up to two to three times the normal amount than you would normally give. If using pill-form supplements of milk thistle, this could be up to 100 milligrams (mg) per 5-pound cat per day.