It is pretty hard to define heroin abuse without looking at the possibility of drug addiction. Most people, if not all people, who are abusing heroin are addicted to it. Pretty much everyone who ingests the drug in any form is going to be a drug addict. People may casually use a drug such as alcohol, but this becomes less likely to see casual use with an illegal street drug such as heroin. If a person is abusing heroin in any form, then they are most likely a drug addict (or becoming one quickly).
Heroin abusers should seek help for their problem. This can be done in several different ways, but one of the best ways to start out the process is to go to a drug rehab facility. There are several reasons for this from the perspective of the heroin addict. One is that they can get you detoxed without the heroin user being completely miserable. Instead of having to kick cold turkey, the medical staff in detox can give you medication that will ease you through the withdrawal process a bit. It is not perfect but it is much better than kicking at home on your couch.
The second reason to seek help for heroin abuse is that in a residential treatment center, you will be protected from the threat of relapse, at least in the short term. This is the whole point of rehab, really. Yes, they have groups and therapy and lectures in order to try and teach you how to live clean and sober, but ultimately you are in a protected space where there are no drugs and alcohol. This is important because on the outside people are far too tempted to relapse.
Finally, treatment is a good idea for the heroin abuser because people need support in order to stay clean and sober, and at most treatment centers they will introduce you to a formula for this support. The basic way that this works is through the 12 step programs of AA or NA. They will introduce you to the meetings while in rehab, and then you can continue to get support from the meetings after you leave them. This is a key component of recovery that far to many people miss out on, and thus are never able to really get a firm grip on early recovery. If you lack this support then you are not likely to stay clean in the short run.