The makers of this herbal supplement used for erectile disfunction claim it is safe for just about everyone and has no side effects, but they don't really state any reason to believe those claims. As far as I know, they don't offer any studies or evidence to back up the claim. Some people have suggested it may not be safe for people with high blood pressure, but two bigger questions come to mind: Is it safe at all? And it is effective or effective enough to justify the risk? I know this isn't a complete answer to your question, but from everything I've seen and read, it's about as complete an answer as you will be able to find.