I've been using this lab for years, my friends do as well with no issues. It is high concentration at 450mg/ml and when I used CL's stuff I had the same issue. I'm thinking it might be my body just not dealing well with the high concentrations but I guess I'll know more after next weeks inj. Last night I had a fever over 101 but feeling much much better today. appetite is back and no fever, still a little achy but not as bad as yesterday.