TweetWell, the rule of thumb is max of 6 weeks. Even at low doese you will begin to train your thyroid that there are higher levels and over a period that long you could cause your thyroid to shut down or work less. 14 weeks is a long time bro. If it were me and I wanted to do something for that long, I would do a T3/clen alternation. I would do the T3 for 21 days, then the clen for 21 days. I would just take 25 mcg of the T3 and 80 mcg of the clen. I know Mikey likes to do the 21 on and off with T3 and he's had good success with it. And, at only 25 mcg a day, it's not long enough or high enough to require ramping or have to worry about thyroid shut down.
Of course, this is just my opinion and not medical advice.