At least some of my drug problems are related to self medication although it's never completely cute and dried ;-
MDMA - years of heavy use IMO partly because it enabled me to feel happiness and relate to others
Speed - Energy and confidence - especially these days it removes the fatigued I suffer gices me motivation and circumvents insomnia ( this is not a recommendation)
Cannabis - 15 years of very heavy daily use - helped my anxiety and calmed me down I gave up on health grounds but over all I think it was a more positive than not mentally
Benzos - a good year or 2 of quite serious abuse, I felt they helped for obvious reasons but in retrospect they made things much worse (responsible use might well be therapeutic)
Coke - a couple of years of regular use, I have nothing good to say about and insidious substance that is best avoided IMHO
Alcohol - about 3 years of problem daily drinking ( bottle of Whiskey a day) horrible made me physically and mentally ill, a very damaging drug used in that way.
Tobacco - nearly 20 years I guess they helped with my nerves, so many people with mental illness smoke, I gave up as I planned to have children
Opiates - the last 12 months I've been taking codeine and morphine, prescribed for pain following a road accident surprisingly I've had pretty much no problems with controlling it and recently CTd from 100mg of morphine a day with little issues.
My drug use has many facets that I've become aware of
I'm a confirmed hedonist and do like taking drugs, it is one of only a few things a derive real pleasure from
Self medication is without doubt a significant factor in some cases and not all of it has negative results but overall I think total abstinence would be better
I believe that there can also be an element of self harm in some cases, I've only come to realise this fairly recently so am trying to address it