By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) - You have probably heard about herbal medications and other over the counter treatments for erectile dysfunction. But you need to remember that just because something is over the counter doesn’t necessarily mean it’s safe. For men on common heart and blood pressure drugs, popping one could lead to stroke or even death.

A major concern is that without regulation there are problems – in particular with some foreign products which may work because they contain unregulated versions of the very pharmaceuticals they’re supposed to replace.

A particular concern is for the millions of men who take nitrates. These are drugs prescribed to lower blood pressure and regulate heart disease. When mixed, nitrates and impotency drugs can slow blood flow from the body and it can cause all sorts of problems, including heart attack and stroke.

My advice is make sure you know what you’re taking.