Having read a few posts related to the question, "Is masturbation harmful?", most of the answers I've seen seem to suggest that the only possible harm could be psychological, in the sense that masturbation may be a distraction from one's normal routine.
What about the actual PHYSICAL side effects? Some things can not be dismissed as mere "wives' tales"! For example, when I masturbate often, I do notice a darkening under my eyes. I am only 28, but having been at this a while, it does seem as though I can not as easily become erect, or stay erect for as long as I used to. I may not have grown hair on my palms, but I have noticed (and I'm willing to concede that there may be no causal relationship here) that I have become somewhat hairier, in all the wrong places.
Please set the record straight as to what, if any, harmful PHYSICAL side effects may result from masturbation, and why, in the face of my testimonial and no doubt countless others, such symptoms as I have described are dismissed by yourself and your peers as "myths."
At the risk of sounding like a broken record, or worse yet, dismissive of your concerns, the real "harm" here is not physical. It's all the worry, shame, and conflict attached to masturbation by so many men, women, and children, thanks to negative associations with all kinds of sex — done by one's self and with others. These messages come from so many influential places — often for most of one's lifetime. It may not be true for you, but this cloud that hangs over many masturbators might send some looking for physical "harm" from this popular practice. It can be a way of justifying any bad feelings and beliefs about masturbation that might never allow going it alone totally okay.
That said, your "blame-it-on-masturbation" reasoning is understandable. If one sprouts hair in "strange" places, sports dark circles under the eyes, and says goodbye to those always reliable erections during and after stretches of solo-sex, one could easily conclude that these unwanted reactions came on as a result of whacking off. Then, could it not also be said that hair loss, far-sightedness, and love handles also owe it to masturbation? And what about greater self-confidence, career changes, and the urge to buy property? The point: is it possible that all of these occurrences stem from something besides genital stimulation? Might aging also be the culprit?
It may not come up 'round the copier and coffee table, but many twenty- and thirtysomethings now include unsightly nose and ear hair plucking in their regular grooming routine. They'd also put down difficulty with getting it up and keeping it there as a getting older symptom. Bags under the eyes? Yep, that's on the list, too.
If you're not convinced that masturbation doesn't play a direct role in the physical "consequences" that you're now experiencing, how about conducting an experiment? Masturbate less often, or refrain from doing it for a few months, and see if your symptoms disappear. NOTE: not "relieving" yourself for an extended period of time may lead to other unwanted physical and psychological situations, including irritability, difficulty concentrating, insomnia, and wet dreams. Now, it is possible that any stress, guilt, disgust, etc. with your personal sex play is making it harder to get and stay hard — these feelings are frequently powerful obstructions to sexual arousal. Also, if you're masturbating past your bedtime, dark circles may stare back at you the next morning.
It sounds as though you've read at least some of the archived Q&As on this subject; for those who have not, check out the related questions, with some varied perspectives on the big M.Alice!