By itself, pure heroin is not as dangerous as, for example, alcohol. One of the significant disadvantages is the strongest addiction caused, as you know, by the incorporation of the drug into the human metabolism. Since pure, medical heroin exists only in countries with legalization and a decriminalized market, the danger in most countries is precisely the impurities that contain, for example, pipolfen, diphenhydramine, antihistamines, and sometimes broken glass, flour, sugar.
By the way, in this country, people most often die not from heroin itself, but from abscesses, phlebitis and overdoses, because it is impossible to correctly calculate the dose of a dirty, loose substance, and therefore an unpredictable (fatal) outcome. If we compare drug addicts in Switzerland, where there are special programs for the distribution of heroin / methadone and disposable syringes, and drug addicts in Russia, then the result is disappointing: the problem of people rotting alive is quite acute. Add to this hepatitis (dirty, street heroin, consisting of anything but heroin), HIV, completely reduced immunity and the impossibility of resisting disease. Drug addicts often use Naphthyzin as a solution for injections - this is generally without comment. I know a couple of people whose limbs rotted alive.
To summarize, I can say: drug addicts in Switzerland look much better than typical alcoholics, do not experience problems with low blood clotting, lack of immunity, overdoses and abscesses. They live with their addiction, but they live acceptable and are not much different from ordinary residents. So the problem is not heroin, the problem is the lack of legalization and medical programs.
I would venture to answer, even if the answer is minus, because I suffer from addiction (but in terms of alcohol), but I think it is important. I recently read Allen Kara's book - An Easy Way to Quit and Drink and there was a very good thought that even moderately drinking people are still alcoholics, just at an early stage of the disease and that this early stage can last a lifetime, but the fact remains - not everyone reaches the "homeless" life for the sake of a bottle. The same is with drugs - someone stays at the first stage all their lives, and someone falls forever and you can never predict whether it will be you or not. Chemicals have a lot of power over us, so there is no "safe" dosage anyway. Everything is relative, depending on your tolerance for the substance (be it a drug, alcohol or tobacco). I would not risk it if I were you. I have a big problem with alcohol and I smoke like a locomotive, so if I try drugs, I will get sucked in there too, so I don't.