Its not easy to have someone who is so. Major headache yan. My late uncle who used to live with us developed that habit due to the crowd he associates with. Mga nabubuhay kasi sa bad businesses though masasabi mo nga na rewarding kasi. As in when they say they went to Hong Kong just to drink coffee ay literally that's what they did.
Youngest kasi siya sa kanilang magkakapatid so my mom was quite protective of him then. Yet, my father (bless his soul) was firm that he will not tolerate someone like that at our place. Thus, kick out na siya.
By then the power wielded by his friends has weakened due to changes in the political landscape. Kaya to make a long story short ay he was forced to go cold turkey.
Nabuhay naman na siya ng mas matino after that though he died just last year due to health complications rin.
Another would be my brother-in-law. Bad crowd rin kasi but he changed his habit after he was left to rot in jail while his so-called friends (and worthless relatives) kinukutya pa siya being stuck in the cell. Made him realize what his "friends" really were.
The first thing then to do is to move them away from the crowd they hang out with. Rehab would be next and strong support must be put into place by those who will be living with them after that rehab. Dahil temptation can still be strong especially when that worthless crowd that "encouraged" him towards that vice visits the subject.
I also have a cousin who was into that. Kasi mga kabarkada niya na in the law enforcement and government offices ang mismong mga ganun. As in they make his home their pot session place. And isipin ninyo isasangla yun service pistol just so they can afford to have another taste of drugs. Mabuti na lang crime then was quite low sa province namin - unlike now na may IEDs na

Ang nangyari sa kanya he got pinned as part of a drug syndicate. In short he became the fall guy. I know he recently left jail na after spending years behind bars for that. Ang mga major movers pa naman ng such sa province namin were what are being headlined then and now as against it. Ha ha, galing ng cover nila ano. Walang direction rin kasi yun buhay ng pinsan ko then. As in binubuhay niya lang sa sabong and those drugs family niya.
Another problem rin ay hindi madali kausapin ang mga yan as the drug addled their brains na nga. Everyday dito sa mga kalye namin sa place namin sa Manila ang dami ko nakikita na naprito ang utak due to drugs. As in parang mga zombies na paikot-ikot. Naglalakad ng walang direction and will latch on someone begging for some money or what. Tapos whole day nakatulala sa sky or something. Actually, these are the lucky ones as others of their kind either went crazy or simply died due to the effects of drugs. The worse part though is that their families now don't care for them. Or have simply abandoned them.
Again, its not easy to fix such a problem but something must be done now before pa maging worse.
Ang definite na alam ko lang something triggered them to seek that vice. Though that is a problem to be tackled na after mapagaling ang subject.
FYI. Back in school we were told to avoid seeking as partners in life ang people who used such substances as chances of having sickly babies was much higher.