Even people who inject themselves with drugs almost always realize the risk of sharing needles, and they do it anyway. That's pretty much what it means to be an addict.
So some places have experimented with making clean hypodermic syringes easy to obtain through a needle exchange program. Anyone who brings in a used one can get a replacement at no charge, with no risk of arrest on drug charges. At first glance this might seem like a way of promoting drug use and a waste of tax dollars, but experience suggests it's the opposite. For one thing, when addicts come in to exchange needles they're usually offered information on treatment programs, and when there are enough openings, a lot of addicts actually do enter them and some -- not all, but enough to make it worth the effort -- wind up getting off drugs.
Of course, needle exchange programs do cost money, but so the spread of HIV, hepatitis, and other infections costs even more. Laws restricting or prohibiting needle-exchange programs are well-intentioned and based on reasonable concerns, but hard experience over decades suggests that in actual practice needle exchange programs reduce cases of dangerous infectious disease while not increasing IV drug use and saving taxpayers money.
Here's more from pediatrician and medical school professor Aaron Carroll:
For sources, click on the link and look at the video's description.