Purified extracts injected intramuscularly, subcutaneously or by intravenous infusion. Unless otherwise indicated, side effects listed are from injected preparations. The FDA considers Viscum album unsafe.

The well-known mistletoe is an evergreen parasitic plant, growing on the branches of some tree species. Shakespeare calls it “the baleful mistletoe,” an illusion to the Scandinavian legend that Balder, the god of Peace, was slain with an arrow made of mistletoe.