An herb of bright yellow, umbrella-shaped flowers, lomatium was widely used among native peoples of North America as a treatment for a variety of infections, especially those involving the lungs. Reportedly, use of this herb protected the Washoe Indian tribe of Nevada from suffering any deaths during the 1917/1918 worldwide pandemic of influenza. It was also said to be useful for pneumonia and tuberculosis.

Lomatium is currently regarded by some herbalists as an effective treatment for many types of viral infection, including HIV, viral hepatitis, colds and flus, acute bronchitis, sinusitis, and herpes. However, there is no meaningful scientific evidence that lomatium is helpful for these conditions, nor indeed that it has any antiviral effects at all. The story mentioned above about the great influenza pandemic of 1917/1918 cannot be taken as meaningful evidence of benefit; like all other great plagues, the influenza pandemic gave rise to innumerable rumors of cures, none of which have held up to scientific testing.

At most, there is exceedingly weak evidence from a small number of test-tube studies hinting hint that Lomatiumspecies might have antiviral properties.1-3 However, tens or hundreds of thousands of substances have shown antiviral effects in the test tube; very seldom do benefits hypothesized from preliminary test tube studies hold up when human studies are performed. Only double-blind, placebo-controlled studies can show a treatment effective, and no studies of this type have been performed on lomatium. (For information on why such studies are essential, seeWhy Does This Database Rely on Double-blind Studies?)