Dandelion leaf is a diuretic and may increase the excretion of drugs from the body. If you are taking prescription medications, ask your health care provider before taking dandelion leaf. If you are currently being treated with any of the following medications, you should not use dandelion preparations without first talking to your health care provider:

• Lithium -- Animal studies suggest that dandelion may worsen the side effects associated with lithium, a medication used to treat bipolar disorder.
• Antibiotics, quinolone -- One species of dandelion, Taraxacum mongolicum, also called Chinese dandelion, may decrease the absorption of quinolone antibiotics (such as ciprofloxacin, ofloxacin, and levofloxacin) from the digestive tract. It is not known whether Taraxacum officinale, also known as common dandelion, would interact with these antibiotics in the same way. As a precaution, dandelion should not be taken at the same time as these antibiotics.