A study conducted by the Southwest Oncology Group which surveyed more than 17,000 men over 55 years of age with a seven year follow-up period, has concluded that long term use of finasteride is unlikely to cause sexual dysfunction for most men who decide to take the treatment. The study focussed on Proscar, which is the 5 mg daily dose used to treat Benign Prostatic Hyperplasia rather than the 1 mg a day dose called Propecia which is used to treat hair loss in men. It seems logical however that if no discernable problems could be detected in the long term with the 5 mg dose, then it is unlikely that the 1 mg daily dose would cause a problem in the long term either.
The study grew out of the Prostate Cancer Prevention Trial which was set up to determine whether finasteride could actually prevent prostate cancer. The trial concluded that finasteride could reduce a man’s chances of getting prostate cancer by almost 25%. It should be emphasised however that finasteride is not licensed for this preventative purpose.
Earlier studies into the effects of finasteride were very short term and did not take into account other factors such as age, medical condition or smoking status. Given the other factors, it was concluded that the small average decrease in sexual function was not an important difference and that much larger differences were simply due to individual variations.