Silybum marianum, commonly known as milk thistle, is an herb with benefits for liver function, according to the University of Maryland Medical Center. People can buy milk thistle extract under the name Thisilyn, a product containing 175mg milk thistle in capsule form, standardized to 80 percent of the active ingredient silymarin. Nature's Way explains that this proprietary extract dissolves more quickly and easily in the digestive tract than other brands, allowing for maximum absorption. Thisilyn may be particularly beneficial for people who drink alcohol, smoke or are exposed to environmental pollutants. Milk thistle is generally regarded as safe, and side effects are uncommon.
Gastrointestinal Side Effects
Some people experience gastrointestinal side effects when taking milk thistle. As listed by the University of Maryland Medical Center and the National Center for Complementary and Alternative Medicine, these effects may include upset stomach and bloating. Milk thistle has a mild laxative effect, which can lead to diarrhea in some individuals, particularly when taking larger doses.
Although unlikely, some people may experience an allergic reaction to milk thistle, according to the National Center for Complementary and Alternative Medicine. This is more common when someone is allergic to other plants in the aster family. These plants include artichokes, chrysanthemum, daisy, marigold and ragweed. Signs of an allergy to milk thistle include a rash or hives, stuffy or runny nose, wheezing or difficulty breathing, and mouth or throat swelling.
Milk thistle, including the Thisilyn brand, contains substances called flavonoids that have estrogen-like activity. The herb may stimulate uterine contractions and menstruation, according to the Memorial Sloan-Kettering Cancer Center, so pregnant women should not take milk thistle. Additionally, the University of Maryland Medical Center recommends that people with a history of hormone-related cancers or who are at increased risk for these cancers not take milk thistle. These cancers include breast, ovarian, prostate and uterine.