600 mg oregano oil extract was orally administered for 6-weeks to 14 patients who had tested positive for the intestinal parasites Blastocystis hominis, Entamoeba hartmanni and Endolimax nana. After the 6 week treatment there was complete disappearance of Entamoeba hartmanni in 4 cases, Endolimax nana in 1 case, and Blastocystis hominis in 8 cases. Gastrointestinal symptoms also improved in 7 of the 11 patients who had tested positive for Blastocystis hominis.
Oregano extract immobilized all of the furcocercariae (parasitic larva) of Schistosoma haematobium exposed to the extract within 15 min. Schistosoma haematobium are parasites found in the urinary bladder.
Mexican oregano (Lipia beriandieri) extract has been shown in vitro to be effective against the giardia parastite, and superior to tinidazol which is a drug of common use in the treatment of giardiasis.