There should be an expiration date on the kit. There was on mine. (I think so) I mixed mine up last year and used some. Then used the remainder 1 year later. (5000iu's) 750 or so per day. Well I didn't really notice much last year. But this year when I used the same mix, I was completely drained for a week which started about 3 days after the first shot. I was doing it in the middle of a cycle. And I could barely drag my ass into the gym. Then about 3 days after the last shot of HCG, it went away. So I don't know if it was from it, or from it being expired or what, but I just think it was too much of a coincedence to think otherwise. (I believe that's the expression)