Commercial oil of oregano is a tricky product; that’s because when all you know is to look for carvacrol in the oil because it makes the antifungal stronger, then what most people would naturally think is, “The more the better.“ But that’s not the case with the carvacrol in oregano oil. What you should look for is “wild” and “natural” oregano oil instead of just looking for the amount of carvacrol it contains; otherwise, if you end up purchasing a brand that contains something like 75-90% carvacrol, then it’s probably been processed that way by a method referred to as fractionating; this is done by literally “boiling off” some of the other components of the oil in order to make the percentage of carvacrol appear higher. The problem with this is that it’s no longer a natural oil but rather a processed oil. The other problem is that the components which were lowered were also important to the quality of the oil, and after the process, there are lower amounts of these components, but not really more carvacrol, just the appearance of more.
The natural amount of carvacrol in oregano oil which is sufficient for human use and potent enough for a strong antifungal can be as low as 60% and in rare cases, as high as 85%. “Wild North American Herb and Spice Oregano Oil P73” which I linked to earlier contains approximately 64% carvacrol.
And yes, Raster, it’s a good thing; you want a natural antifungal if you can get it. Some natural and strong antifungals are pure garlic, rutabaga, grapefruit seed extract, and of course, oil of oregano (there are more, but these were the first that came to my mind).