Mistletoe is unlikely to be the wonder cancer treatment that many had hoped for, according to doctors.
Studies have provided little proof that extracts of mistletoe can be used to target cancer cells, and doctors warn that the plant could even be harmful.
Some countries use extracts in complementary medicine regimes as proponents believe that regular injections can slow down and even stop cancer growth.
However, an article in this week's British Medical Journal (BMJ) suggests that faith in mistletoe may be misguided.
Edzard Ernst, professor of complementary medicine at Plymouth and Exeter Universities, warned that previous studies have been "methodologically weak", meaning that they are more likely to produce a positive result.
Claims are often not supported by good evidence, he said, and independent reviewers have noticed that patients often experience joint pain, ulcers and kidney failure.
"Thus, mistletoe has been tested extensively as a treatment for cancer, but the most reliable randomised controlled trials fail to show benefit, and some reports show considerable potential for harm," he said.
In addition, Professor Ernst said that regular mistletoe injections were costly and concluded that the plant should "not [be used] as an anticancer drug".