Benign prostatic hyperplasia (BPH) is a common condition among aging men that causes lower urinary tract symptoms (LUTS) and may negatively affect sexual function. This randomized single-blind controlled clinical trial compares the efficacy, safety, and sexual outcomes of different dosing regimens of tadalafil or tamsulosin combined with 5-alpha reductase inhibitors (5ARIs) in men with BPH and enlarged prostate volume. A total of 240 participants were randomly assigned to six treatment groups and followed for 12 weeks. Changes in urinary symptoms, erectile function, ejaculatory function, prostate volume, prostate-specific antigen (PSA), urinary flow rate, post-void residual volume, and adverse events were evaluated to determine the optimal combination regimen.