Oregano can certainly be taken internally. The oil is just more concentrated than the leaf, which is what most people use when cooking. The oil should be diluted when taken internally or put on sensitive areas of the body. I think companies just try to protect themselves from law suits and avoid problems with the FDA, so they say not to take anything internally. If aspirin were just now being "discovered" and marketed, it would probably be illegal. Of course, most pharmaceutical shouldnt' be taken internally and should be illegal (in my opinion).I always thought Oil of Oregano isn't recommended to be taken internally?
For topical use as an antiseptic, I use it for cuts and such.