BPH二重経口療法：メカニズムとその副作用

最終更新日： 2026年5月18日

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Benign Prostatic Hyperplasia (BPH) is a degenerative condition of the prostate gland that no aging gentleman can escape. According to epidemiological data, BPH affects 42% of men aged 51–60, over 70% aged 61–70, and nearly 90% aged 81–90. Today we discuss the “dual oral therapies” approach to BPH management.

• 泌尿器センター バンコク病院 タイ オンライン予約 02-310-3009 bhquro@bdms.co.th
• サミティジ・シラチャ病院 チョンブリ 088-022-1445

BPH commonly presents with weak urinary stream, frequent nighttime urination, and other lower urinary tract symptoms (for a full overview of BPH symptoms, see this article). While BPH is not life-threatening, it significantly impacts quality of life. Oral medications have advanced considerably — today we focus on the dual therapy approach.

BPH Dual Therapy: Alpha-blockers + 5-Alpha Reductase Inhibitors (5-ARIs)

1. アルファ遮断薬 (e.g., Silodosin, Alfuzosin, Tamsulosin, Doxazosin)
   • Mechanism: Rapidly relax smooth muscle in the prostate and bladder neck, widening the urethra and improving urine flow. Symptom improvement can occur within hours to days. Both the American and European Urological Associations recommend Alpha-blockers as first-line BPH treatment
   • Side effects: Dizziness (antihypertensive-like effect); abnormal ejaculation; importantly, Alpha-blockers do NOT cause erectile dysfunction

2. 5-Alpha Reductase Inhibitors (5-ARIs) (e.g., Dutasteride, Finasteride)
   • Mechanism: Block the conversion of testosterone to dihydrotestosterone (DHT), which is the primary driver of prostate gland enlargement. Reducing DHT gradually shrinks prostate tissue. After 6 months of regular use, 5-ARIs achieve up to 30% prostate volume reduction and 50% decrease in PSA values. They also reduce long-term BPH complications including risk of acute urinary retention and the need for surgery
   • Side effects: Reduced libido (due to DHT interference); erectile dysfunction (due to DHT interference)

The two drug classes complement each other: Alpha-blockers provide rapid symptom relief but do not reduce long-term BPH progression. 5-ARIs work slowly (6+ months) but have proven efficacy in reducing long-term complications. Combined dual therapy delivers both immediate symptom control and long-term disease modification.

Any questions about BPH medication, discuss with your trusted urologist or contact me through the social links on this website.

Frequently Asked Questions About BPH Dual Oral Therapy

What is BPH dual therapy and why is it used?

BPH dual therapy combines two drug classes: an Alpha-blocker (for rapid symptom relief) and a 5-Alpha Reductase Inhibitor or 5-ARI (for long-term prostate shrinkage and complication reduction). Alpha-blockers alone relieve symptoms quickly but do not slow BPH progression. 5-ARIs alone take 6+ months to show effect but reduce the risk of urinary retention and surgery. Combined, they provide both immediate and sustained benefit, making dual therapy the preferred approach for men with moderate-to-severe BPH, especially those with larger prostates.

What are the side effects of BPH dual therapy?

Alpha-blockers commonly cause dizziness (due to blood pressure-lowering effect) and abnormal ejaculation, but notably do NOT cause erectile dysfunction. 5-ARIs can cause reduced libido and erectile dysfunction through their interference with DHT, the androgen hormone responsible for prostate growth. When both are used together, patients may experience a combination of these side effects. The type and frequency of side effects vary between specific medications within each class, so individualized selection by a urologist is important.

How long does it take for BPH dual therapy to work?

Alpha-blockers typically begin improving urinary symptoms within hours to days of starting treatment. 5-ARIs require approximately 6 months of regular use to achieve meaningful prostate shrinkage (up to 30% volume reduction) and PSA reduction (up to 50%). Long-term complication reduction — such as lower risk of acute urinary retention and surgery — builds progressively with continued 5-ARI use. Dual therapy must be taken consistently and long-term to achieve its full benefit.

If you are experiencing urinary symptoms from BPH and would like to discuss medication options including dual therapy, Dr. Soarawee Weerasopone offers specialist consultations at Bangkok Hospital Headquarters. 診療をご予約.

**免責事項:** このコンテンツは、バンコク病院本部の認定泌尿器科医であるSoarawee Weerasopone博士によって作成およびレビューされました。教育目的のみのものであり、医学的アドバイスを構成するものではありません。いかなる医療処置を開始する前にも、必ず資格のある医療専門家にご相談ください。.