Duration of effect matters when it comes to successful treatments.
If we take your position and apply reductio ad absurdum, we could say that cocaine is a highly effective treatment for anxiety, although of course we know that in the not-so-long run it has the opposite effect.
Shouldn't that be up to bodily autonomy? If someone feels that cocane relieves their symptoms then who is the doctor to say that they don't. Perhaps releaving those symptoms even for a short period of time is worth the consequences.
But a lot of psychatric treatments are just that. Treatment for ADHD for example is giving ampethamines (which btw are chemically no different than a low dose of meth), which have a duration of 3-6 hours and its back to worse than baseline after the effect has worn off.