persistence of symptoms after discontinuation is the big one. after hormone levels return to baseline, there's no more pharmaceutical effect. thus the cause of those symptoms is unlikely to be pharmaceutical.
it's worth noting that candidates for finasteride treatment are already likely to be older and dealing with comorbidities like depression and anxiety, which makes it harder to say for sure if it's the drug in a lot of cases, but they do seem slightly higher than placebo. it is not surprising that a sudden change in hormone levels would cause a noticeable change in mood or sexual function, but there is usually improvement with continued treatment as levels stabilize.
for persistent effects, really there isn't a lot of reliable data to go on, and no plausible mechanism of action. we have a handful of anecdotal reports and some armchair hypotheses.
i'm happy to be proven wrong, and lots of drugs are indeed implicated in serious and lasting side effects, but in the case of finasteride i'm not convinced.
"after hormone levels return to baseline, there's no more pharmaceutical effect" Maybe no longer directly, but with one level of indirection there certainly _could_ be.
"no plausible mechanism of action" - I haven't looked into it to understand the mechanism of action for side effects from finasteride, but certainly if it can cause side effects during use, those could impact the body in a way that causes effects that persist past when usage stops.
Same with almost anything harmful that we do to our body - ideally the damage or effect is healed and we return to baseline, but very often we don't.
There could also be an effect where someone tried it, it didn't work as well as they wanted or it caused a side effect, and this was psychologically difficult to deal with and helped lead to depression and anxiety without that being directly chemically caused by the drug. And it would be fair to argue that that's not the drug's fault.
it's worth noting that candidates for finasteride treatment are already likely to be older and dealing with comorbidities like depression and anxiety, which makes it harder to say for sure if it's the drug in a lot of cases, but they do seem slightly higher than placebo. it is not surprising that a sudden change in hormone levels would cause a noticeable change in mood or sexual function, but there is usually improvement with continued treatment as levels stabilize.
for persistent effects, really there isn't a lot of reliable data to go on, and no plausible mechanism of action. we have a handful of anecdotal reports and some armchair hypotheses.
i'm happy to be proven wrong, and lots of drugs are indeed implicated in serious and lasting side effects, but in the case of finasteride i'm not convinced.