alright so my gf and i have used iv heroin on and off over the past year currently on. We are generally pretty careful and keep emergency naltrexone syringes in case of overdose and make sure there is ample time between each of us using to detect overdose. We have always used together and always the same dose. We accomplished that by taking the amount of powder we want for both of us and dissolving it in 60 units of water thrn after filter we would split it 30-30. So suffice it to say we have similar tolerances if anything hers is higher than mine as illustrated by the effect the high has on either of us. im generally more apt to nod and experience all of the other side effects, but its pretty even. for the record i am 5'11" 200 lb and she is 5'8" 120lb. Earlier today we had gotten some stuff from our dealer which i believe was fentanyl. we have gotten the same stuff times before and while the rush is very similar the duration of action is an hour at most compared to the usual 4-6 hours for the actual stuff. We prepared it like normal and 5-10 minutes after injection she became unconscious, started turning blue, experiencing respritory arrest and severe bradychardia (20-40 bpm). I revived her with our emergency naltrexone shot but im curious as to why it had little to no effect on me and nearly killed her. after the rush i felt little to nothing. does anyone have any ideas?

