I had this in my email from a very decent hair transplant surgeon who felt that it was his duty to alert his patients to the findings of this study which notes that long term use of finasteride was a bigger risk factor for permanent erectile dysfunction than other risk factors such as smoking or diabetes. Definitely something to consider and confirmed my belief that taking a 5AR is not particularly healthy and that all risks versus benefits should be carefully assessed:
"Our data show that, in a cohort of men exposed to 5α-RIs, the duration of 5α-RI exposure was a more accurate predictor of PED than many known risk factors, including age, hypertension, diabetes mellitus, cigarette smoking, ethanol abuse, obesity, and depression. In our data, confounding by age or extent of healthcare utilization did not account for the increased risk of PED associated with longer 5α-RI exposure duration (Table 3, Figs. 2A and and2B).2B). Also, duration of finasteride exposure proved to be a more accurate predictor of sexual dysfunction than higher dose vs lower dose of finasteride, likely reflecting that finasteride exerts near-maximal inhibition of 5α-DHT synthesis at a dose of 1 mg"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5346286/
"Our data show that, in a cohort of men exposed to 5α-RIs, the duration of 5α-RI exposure was a more accurate predictor of PED than many known risk factors, including age, hypertension, diabetes mellitus, cigarette smoking, ethanol abuse, obesity, and depression. In our data, confounding by age or extent of healthcare utilization did not account for the increased risk of PED associated with longer 5α-RI exposure duration (Table 3, Figs. 2A and and2B).2B). Also, duration of finasteride exposure proved to be a more accurate predictor of sexual dysfunction than higher dose vs lower dose of finasteride, likely reflecting that finasteride exerts near-maximal inhibition of 5α-DHT synthesis at a dose of 1 mg"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5346286/