I actually looked into using it because of a book my wife read. She had had a total hysterectomy and the estrogen that her Dr.'s prescribed made her symptoms 20x worse. So she looked at alternatives. This book (don't remember the title), made a brief reference to progesterone use in men. I have been looking for answers to my condition since my Dr. gave me Viagra 12 years ago. I was (and still am) very tired of the "Vigraines" as my wife's old boss at the health food store used to call them, every Time I use one of the little blue pills. My research led me to the research of the late Dr. Lee. I just decided to try progesterone to see if it would help. Not sure it really helps my ED, but I did notice my "guys" stopped shrinking and I felt a lot better. No, i haven't experienced any negative symptoms. But as I said, I'm battling a very different problem than most guys. (I've only met one other person who has a tumor. She is an elderly neighbor, in her 90's who is seeing the Dr. that removed mine). There is actually very little info on my condition, at least I haven't come across much, and I've been searching since I had surgery 2 years ago.