You are arguing, in essence, that the existence of social services that transfer costs for individual health-harming decisions to the populace in general (which I oppose, by the way) means that you no longer "own" your body and society has the right to impose restrictions on your behavior in order to protect its own interest in your health. Recognize that the exact same argument could be used to justify government prohibitions on auto racing, Big Macs, sugary snacks, and to justify government mandates on seatbelts, helmets, toothbrushing, and/or just living in hermetically-sealed plastic bubbles.
Again, I don't like the gradual erosion of our culture of personal responsibility. If someone is dumb enough to harm himself -- by injecting heroin, drinking alcohol, smoking tobacco, racing an automobile, or jumping out of an airplane with a not-infallible parachute -- let him assume that risk, and let him bear the associated costs. But just because I'm a minority in this viewpoint and because the democratic majority has decided to require society to bear some of these costs is no justification for restricting personal liberty.
No, I am arguing that by taking certain actions (abusing drugs), you have forfeited some of your right to "own your body", not because of your health, but because the health and welfare of other citizens is effected. Does my right to swing my fist end where your nose starts? No rights are absolute; they end where they start to adversely infringe on the rights of others. Drug abusers do this constantly.
The problem with drugs is that, with a great many of them, there is a loss of control over one's actions. How do you simultaneously allow people to do something that deprives them of control of their actions, and hold them responsible for those same actions? Either you have to place drug users out of the protection of society, or society has the right to defend itself from the behaviors of the drug users. Either Society isolates the users, or they isolate themselves while abusing. I have no faith in the druggies voluntarily isolating their own damage.