Because of the way it works to decrease DHT levels, and because DHT is very important in sexual function, it has a known potential side-effect of erectile dysfunction. Despite this potential side effect, finasteride is still considered first line therapy for BPH, regardless of TRT usage. That's because it really works, really well. However, if you are unlucky enough to suffer from the side-effects, then they are typically severe enough to need to stop using it.There is a recognized, though not fully understood phenomenon known as post-finasteride syndrome, where a man will get the side-effect of erectile dysfunction while on the medicine, and then stop it, and still have ongoing problems with erectile dysfunction. There is no known scientific reason for this, as physiologically speaking, DHT levels return to normal after cessation of the medicine. The working theory is that men will have ED, then develop performance anxiety after being unable to perform previously.In fact, placebo controlled studies have found that the incidence of the symptoms found in post-finasteride syndrome were higher in the placebo group than the control group.Another large nocebo study where they educated a group of men about the sexual side effects before starting treatment, compared to a group of men who started treatment without this education, showed that 43.6% of the patients who were informed presented symptoms (nocebo effect), compared with 15.3% of the other group who were not informed. Meaning that just the suggestion that symptoms could occur while on the medication were enough to triple the incidence of people who got symptoms.Long story short, it appears that finasteride is being blamed for performance anxiety, and there is no scientific reason why any man would have persistent symptoms after cessation of the medication, though enough men complained about it that the FDA now requires it to be listed on the package insert of the medication as a potential complication.If you want to avoid this issue, then using alpha-1 blockers like tamsulosin will help with symptoms of BPH with a very limited side effect profile.