Drug addiction is a bit impossible to cure as what most people say but to be honest, we could still find means to help those that are under the influence of Marijuana. Those people who have been in the rehabilitation should be treated well and fair because these are the kinds of people that tend to withdraw from social interaction as their need and use for drugs increases everyday be it in frequency or in quantity. As their tolerance began to sprout they also long to crave for more pots or marijuana. So it is optimal that we treat them nicely and try to understand them as well. Try to explain to them in the most subtle way why they should refrain from taking these illegal drugs in their system.
Those that are under the category of heavy users are often the most depressed and have more intense mood swings that is why it is better to treat them well and give them the required immediate medical attention especially if they are already overdosed to it.
You can also talk to them and give them advices to motivate on stopping the use of marijuana especially when they have already started rehabilitation. Offer them help or get him into a professional therapist who facilitates the intervention when you have already failed to rehabilitate your friend or someone from your family. Intervention actually helps a lot in the process so as to recognize the severity of marijuana addiction and how it can ruin his or her relationship with the people around them.
Although this may be a long process to make but with determination to recover from such an addiction and with the fervent help from the immediate family, soon enough the patient will eventually recover. Constant guidance and talking with him or her also helps them to go through this change. It helps them understand why they need to fully recover such addiction so as to put their lives in the right direction.