I have heard of all kinds of products usually with exotic non studied component.  (Thistle extract with ginger and ...etc.) Patients think physicians understand these things. The point is none is ever studied by the FDA and  they often say: "This product is not meant to diagnose, prevent, or treat any condition."
I am amazed at patients who read everything about any new medication I recommend (which is a good thing) who will gladly take something recommend by "Louie" at the natural health store or "Dr." (usually a mail order doctorate of naturopathic medicine or some other such thing,) Jim on the radio.
This is like flying on "Take a Chance" Airlines.

My experience has been that, when these OTC counter products work, they have managed to sneak in an extra ingredient (usually some of the Viagra or Cialis compounds).  Check out the linked page from the FDA.  They have a pretty aggressive interdiction program.  Rhino and others work until they are caught.  

For my money, I would go with the real thing either here in the U.S. or bought OTC when you're overseas