Milk thistle is considered safe for most people, but those with ragweed allergies may experience a rash or even severe allergic reactions when taking the herb. Other side effects include diarrhea, bloating, nausea, gas and upset stomach. Women with a history of ovarian, breast or uterine cancer should not take milk thistle because it mimics the effects of estrogen, according to the WebMD website. WebMD reports no contraindications for taking milk thistle with other herbs or medications.
Some people can develop mouth sores as an allergic reaction to dandelion root. Those with ragweed allergies or allergies to yarrow, daisies, chrysanthemums, chamomile, yarrow and iodine may experience allergic reactions as well. This herb is generally considered safe; however, the diuretic properties of dandelion can increase the elimination of drugs from the body. Consult with your prescribing physician if you are taking medication. Dandelion root is contraindicated if you are taking lithium, antibiotics or antacids.
Yellow dock is an extremely safe herb to take in recommended dosages. Side effects include loose stools or mild diarrhea. No drug interactions of concern exist with yellow dock, according to "Prevention" magazine.