The oil of oregano is a powerful medicine, topically and internally.
This oil when taken over a period of time (12 days, do not take for extended periods, or if pregnant) internally will kill bacterias, parasites and viral invasions. It will also kill the good bacterias in the gut we require for digestion and assimilations.
If you choose to take oregano, remember to reintroduce lots of probiotics, after you cease taking the oregano.