tl;dr While it can have undesirable side effects, these are long-term. But these side effects make it a powerful nocebo for some people to the point where they almost instantly get side effects (nausea, anxiety, sexual dysfunction), despite that being pharmacologically improbable.
It's mostly nocebo, they read about it online for weeks and then try it, and at that point they are so psyched out that they keep watching for every little thing, effectively making it a self fulfilling prophecy.
I started dutasteride when I was 20 and have been on it for many years and it really stops hair loss, because my hair loss was very fast and aggressive.
So if someone after two weeks had their semen consistency change to be completely watery, would it be their eyes that produced the nocebo effect or? Or how is the doctor who went on it for a few months, lost erections, then gained them back after quitting explained by a nocebo?
Again, I've heard at least 5 of these first-hand, which is kind of wild for a drug I've probably only talked to 20 people about in total.
We're terrible at detecting changes over long periods of time. If anything I'd think long term users would be much more liable to bias.
