5 Alpha Reductase Inhibitors (5ARIs) Monotherapy and Combinations: Current Role in Benign Prostatic Hyperplasia (BPH) Management

Background and Objectives: Benign prostatic hyperplasia (BPH) is a progressive, androgen-dependent condition driven by dihydrotestosterone (DHT). 5α-reductase inhibitors (5-ARIs), including finasteride and dutasteride, target this pathway and provide disease-modifying effects. Materials and Methods: This narrative review summarizes evidence from randomized trials, meta-analyses, and observational studies evaluating the efficacy, timing, and safety of 5-ARIs in the management of LUTS due to BPH. Results: 5-ARI therapy reduces prostate volume by 18–28% and serum PSA by approximately 50% within 6–12 months. Landmark trials (MTOPS, CombAT) demonstrate significant reductions in acute urinary retention (AUR) and BPH-related surgery (>50% RR reduction). Combination therapy with α-blockers provides superior symptom control and greater prevention of clinical progression, particularly in men with prostate volume ≥ 30–40 mL or PSA ≥ 1.5 ng/mL. Early initiation of combination therapy improves long-term outcomes, while α-blocker withdrawal may be feasible in selected patients. Adverse events are mainly sexual, with emerging data suggesting a possible association with depression. Conclusions: 5-ARIs are central to BPH management, offering sustained clinical benefits and prevention of progression. Optimal outcomes depend on appropriate patient selection, early treatment in high-risk individuals, and individualized long-term strategies.