Possession of more than 100 grams of heroin or a mixture containing heroin in the United States, is punishable with a minimum mandatory sentence of 5 years of imprisonment in a federal prison.
Significant tolerance to respiratory depression develops quickly with continued use of heroin and is lost just as quickly during withdrawal. This is why it is often difficult to determine whether a heroin death was an accident, suicide or murder.
Street heroin is known to be unpredictable in purity. This means that the user may prepare what they consider to be a moderate dose while actually taking far more than intended. If this occurs and the user takes a dose comparable to their previous use, the user may experience drug effects that are much greater than expected, potentially resulting in a dangerous overdose.