Cannabis - No! That is something I gave up because one day I started feeling alarmingly weird, dizzy and disorientated. This is complete madness, not just because of the drug and its effects, but because of the disorganised, chaotic lifestyle of drug users. I know a few people who continued using cannabis well into old age. In every case, they are less than they could have been.
I believe that all mind altering drugs are harmful. The ideal psychiatric system would be Open Dialogue, a non-invasive method with a very minimal use of drugs. ANY mind altering drug is just a short cut, panic measure, which might work for a short time, but with unpredictable and often very disastrous long-term effects.