None of them have been proven in scientifically controlled double blinded trials. The general feeling amongst specialists is that penile size is genetically determined and fixed at puberty. The ones that do “work”, don’t really increase the size of the penis. What they do is engorge your own penis so their might be a slight increase in girth but this is still your own penis getting to its maximum potential.
Penile pumps tend to engorge the penis temporarily and have no permanent result and if used to excess or incorrectly may damage the penis. I have met some men who say that their pumped up penis is permanently larger, but I have found no proof of this.
According to a doctor in the field … there is no known scientific evidence to prove that any of the pills work. There are only anecdotal stories. “The big one that got away.” So save your money, and more importantly, focus on things that you can control.
If you still feel like you want that extra ‘oomph’, there is one proven way to non-surgically increase the size of the penis - lose weight. If you feel the base of the penis you will note that there is a fat pad which can be up to 2 inches in depth, losing this will increase the size of your penis by that amount. Giving up smoking can also increase engorgement (as smoke is a vasoconstrictor) and therefore allows your penis to get to its maximum potential. Cock rings offer a safe way to increase your girth temporarily. Finally, shaving your pubic hair can give the appearance of a larger penis.