Common and infrequent side effects of dandelion root are unknown, and rare side effects include contact dermatitis, diarrhea and irritation of the stomach or intestines, states WebMD. An allergic reaction can occur in those who are allergic to ragweed, daisies, marigolds and chrysanthemums.
Dandelion leaves, petals and roots are ingredients in medicine for many conditions, including intestinal gas, upset stomach, viral infections, muscle aches and constipation, although scientific evidence does not support or disprove that this is an effective form of treatment, according to WebMD. Some people use dandelion to treat serious conditions, such as cancer, while other people use dandelion root as a substitute for coffee. In food, dandelion is an ingredient in salads, soups, wines and teas. Dandelion also contains a significant amount of potassium, which can lead to too much potassium in the body.
Some types of antibiotics and lithium interact with dandelion, explains WebMD. Some antibiotics that may interact with dandelion include ciprofloxacin, enoxacin, norfloxacin and sparfloxacin. A person taking lithium can experience serious side effects when using dandelion, as dandelion decreases the body's ability to get rid of lithium and results in the drug building up in the system. Additionally, water pills and medications changed by the liver interact with dandelion. This includes Ativan, acetaminophen, Lipitor, Zofran and Haldol.