Lomatium is primarily found in western North America, although related species grow in other areas. Several species are used for medical purposes, including Lomatium dissectum and Lomatium suksdorfii. The latter is an endangered plant. Aboriginal Peoples of western North America used lomatium for medical as well as ceremonial purposes. They applied it directly to wounds to help prevent infection and made tea from its roots to treat respiratory infections and congestion. The plant's roots continue to be used by some Aboriginal healers for viral infections, including HIV.
Test-tube studies indicate that Lomatium dissectum is a powerful antiviral, and compounds isolated from Lomatium suksdorfii have been shown to specifically inhibit HIV. Herbalists and healers experienced with these herbs believe they may also stimulate the immune system. Lomatium is considered powerful and should only be used with the guidance of an experienced practitioner. It contains anti-clotting substances and may be dangerous if your platelets are low or if you have problems with nose bleeds or heavy menstrual bleeding. Lomatium is generally not recommended during pregnancy. High doses may cause a rash resembling the measles.