Getting larger veins is "normal" for those who practice PE techniques, especially jelqs. Most men like the increased size and number of penis veins since they feel it looks "meaner" and might add a bit to a woman’s pleasure.
I did a web search for "vitamin K cream" and found nearly 7,000 sites. Most of them were selling it. And almost all of them claimed that it would reduce skin discoloration from "spider veins" and that it would help reduce varicose veins. I looked at a number of the sites and not one had any documentation to back up these claims.
I then looked at some consumer medicine sites and found this article at WebMD.com. In the last paragraph on the second page they talk about holistic treatments for varicose veins including gingko biloba and vitamin K. The cream is not mentioned, but the authors have doubts that these things work.
I can’t imagine why vitamin K, which in it’s injectable form promotes clotting, would be of any use in reducing the size of veins. Especially not in the form of a skin cream.
My opinion is that you’ll just have to accept the veins or go to a different type of exercise. Of course you’re welcome to give some of these companies your money, but I seriously doubt you’ll see any difference by using the cream on your dick.
