If you are currently being treated with any of the following medications, you should not use dandelion preparations without first talking to your healthcare provider.

Lithium
Animal studies suggest that dandelion may worsen the side effects associated with lithium, a medication commonly used to treat manic depression.

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, or 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.