BackgroundIt is uncertain how long combination therapy should be continued in patients with benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). We investigated the withdrawal effects of α1‐adrenergic receptor blocker (AB) or 5α‐reductase inhibitor (5ARI) following successful combination therapy.MethodsThis prospective, randomized, open‐label, parallel trial enrolled 222 patients with BPH/LUTS who showed at least a seven‐point improvement in International Prostate Symptom Score‐total (IPSS‐T) and a ≥ 20% reduction in prostate volume (PV) following the initiation of combination therapy. Patients were randomized in a 1:1:1 ratio into continued‐combination, AB‐withdrawal, and 5ARI‐withdrawal groups. IPSS, overactive bladder symptom score, EuroQol‐five‐dimensional questionnaire (EQ‐5D‐5L), EuroQol‐visual analog scale (EQ‐VAS), prostate volume (PV), maximal flow rate, postvoid residual urine (PVR), and prostate‐specific antigen level were assessed every 6 months for 24 months. The predictors of IPSS‐T deterioration were evaluated.ResultsAt Month 24, IPSS‐T deterioration (≥2 point) was observed in 20/72 (27.8%) and 19/72 (26.4%) patients in the AB‐ and 5ARI‐withdrawal groups, respectively. Among them, 4/72 (5.6%) and 4/70 (5.7%) patients required readdition of the withdrawn drug (p = 0.868). In the continued combination group, EQ‐VAS improved at Month 24 compared to baseline (p = 0.028). At Month 24, the AB‐withdrawal group showed improvements in EQ‐5D‐5L, EQ‐VAS, and PVR (all p < 0.005), while the 5ARI‐withdrawal group showed improvement in IPSS‐S (p = 0.011). Diabetes mellitus was associated with IPSS‐T deterioration at Month 24 (p = 0.020).ConclusionsIn patients with BPH/LUTS who are reluctant to continue combination therapy, AB or 5ARI withdrawal may be offered in men with improvement in IPSS‐T by at least seven points and reduction in PV by at least 20%.