Well, I ran tren for a year straight once. I took little breaks of about two weeks every few months. At first, everything seemed fine. After a while though, my kidneys were hurting all the time, especially at night. Plus, my pee was a nice shade of brown, even with a shitload of water. Knowing what I know now, I wouldn't do tren for more than 4-6 weeks at a time. Your kidneys are too valuable to risk.