Although most people think of dandelion (Taraxacum officinale) as a pesky weed, the plant has long been used in herbal medicine to aid in digestion and help stimulate appetite. The entire dandelion plant from root to blossom is edible with a slightly bitter, chicory-like taste. The root itself is sometimes roasted to create caffeine-free dandelion coffee. When used for medicine, the dried or fresh root can be made into teas, tinctures, decoctions (infusions), and poultices. Dandelion root is also available over the counter in capsule form.
Despite its long-standing use in traditional medicine, there is a lack of scientific evidence supporting the medicinal use of dandelion root. While a number of animal and laboratory studies have been conducted, few have progressed to human trials.
Diuretics, also known as "water pills," are commonly used to treat high blood pressure, heart failure, liver disease, and some types of kidney disease. While valuable, the drugs may cause side effects, including muscle cramps, headaches, dizziness, and changes in blood sugar.
A 2009 study, overseen by the National Institutes of Health, found that a single dose of dandelion extract increased the frequency of urination—but not the volume—in the 28 volunteers within five hours of a dose.
A 2015 study from Canada reported that dandelion extracts are able to block harmful ultraviolet B (UVB) radiation when applied to the skin, protecting it from sun damage while lowering the risk of skin cancer.
A 2016 review of studies from Aarhus University in Denmark suggested that dandelion extract also stimulates pancreatic cells to produce insulin, better controlling blood sugar and avoiding hyperglycemia.
Dandelion is often consumed as a tonic under the presumption that it "cleanses" the liver. There is some evidence, albeit sparse, to support this long-standing claim.