Most street heroin is actually cut down fentanyl. There is very little "real" heroin anymore in the U.S. Since it is almost impossible to cut evenly, overdose is very common. I strongly discourage anyone from trying or using fentanyl or what is represented as "street heroin", not because "drugs are bad", but because "you may very well die, like, right now". I personally am a proponent of full legalization, so that drugs can be standardized, and people would know what they are getting.