for me it all depends . I had some ug lab stuff that after a month of suffering for 3 days after each injection I had to just never use it again. Then I have used other test/sust that it only happened with the first injection.
at least i know what it is.. read about serum sickness just your body adjusting to the serum level chages .. I feel like shit now ..always get a sore throught and little cough ..