This is a very well written and researched article. Unfortunately the Heroin User's Handbook is out of print so it is not a great reference to cite. Heroin is relatively harmless to one's health. For those who doubt the accuracy of the statement I will point you to two sources:
The Consumers Union Report - Licit and Illicit Drugs. by Edward M. Brecher and the Editors of Consumer Reports Magazine (available online at the Schaffer Library of Drug Policy) [Link]
The Heroin Solution by Arnold Trebach (Review here)
Dr. Arnold Trebach informs us that "putting aside the problem of addiction, the chemical heroin seems almost a neutral or benign substance. Taken in stable, moderate doses, it does not seem to cause organic injury, as does alcoholism over time."
Now understand that there is nothing particularly special about heroin compared to other narcotic analgesics. Heroin converts to morphine in the body and is very similar to other opiates like percocet or vicodin. These medicines are all derived from the opium poppy and can be thought of as the 'essence' of opium (ie concentrated opium). The long term health effects are very minimal and far less toxic than those of tobacco or alcohol.
The arguments put forth against this assertion are either:
I. That can't possibly be true! I just KNOW that heroin is bad for your health! Research? I don't need no stinking research!
II. I have experience with heroin, either personally or with a family member, and I have seen it ruin lives. This is a valid point and emotionally appealing, but does not fit the evidence. For one there is undoubtedly a population of opiate addicts who function quite well but don't come to the attention of law enforcement or the medical profession. They may be independently wealthy and able to afford black market prices or get a regular supply from a sympathetic doctor. Others do well on methadone or suboxone. Given the taboo around narcotic addiction its not surprising this aspect of their lives is not well known. Therefore the only opiate addicts popular culture is exposed to are the so-called 'skid row junkies.' Combined with drug war propaganda this gives an incomplete and discriminatory view of the diverse lives of opiate addicts.
The other point I would make is that the social circumstances in which drugs are used greatly influences outcomes. Many drugs are addictive but how that affects behavior depends on the supply as well as the pharmacology. Some opiate addicts prostitute themselves or steal to fund their habit, I do not dispute this. However this is not a result of the drug's pharmacological action as much as its price. Let's face it, heroin isn't cheap especially once tolerance sets in.
What would happen if there was a tobacco shortage either due to a new prohibition? If cigarettes went up to $5 each ($100 packs) would a lot of smokers stop? Sure, but some would not stop and suddenly police would be chasing tobacco-dependent prostitutes, dealers and petty criminals. Criminal gangs would start extracting the nicotine and developing more potent products. People would start injecting nicotine. Some would overdose, others would be exposed to blood-born infections.
Don't believe that nicotine is as addictive as heroin? See what happened when Germany ran out of tobacco during the world wars. In the former USSR a tobacco shortage resulted in riots. Political oppression, high unemployment and bread lines were all accepted as realities of living in the Soviet Union, but take away their tobacco and all hell breaks loose.
Heroin may be addictive for a minority of people who use it, but how society treats opiate addicts has huge ramifications for how they will process that experience. Prior to 1914 opiates were legal widely used and posed little to no threat to society. Addicts were not ostracised, marginalized or criminalized. They were allowed to continue existing as valued members of the community and because opiates were legal and cheap there was no deviant criminal subculture associated with their use. Heroin-related crime was unknown.
Heroin and pharmaceutical opiates are not going to disappear from the world. Given their efficacy in treating pain (and other things) we would not want them to. Some people will get addicted to them. If that person was you or a loved one, what time period would you want to be living in, pre- or post-1914?