Can the cut in heroin cause hives?

Yes, of course. Because 'cut' can be anything the question is really can ANYTHING cause hives? The answer is then yes, if course. Common 'cut' in powder heroin can be talc powder, baby formula, chalk, caffeine, etc. Common 'cut' in tar is pepsi concentrate, coffee, brown sugar, etc. But, drug dealers are known to step on a batch with much worse things to increase to profits of a batch. So, there is always the potential for hives.

Recommended precaution: 1. Don't do drugs. 2. If #1 is not an option, try a small amount of a new batch for reactions before doing your normal dose. If hives are present take benadryl to help eliminate them. If you know your batch causes hives take benadryl 30 minutes before your dose.