Proscar vs Flomax
Two treatments for an enlarged prostate: one shrinks the gland slowly over months, the other relaxes the muscle and works within days.
At a glance
Key differences
- Different classes. Proscar is a 5-alpha reductase inhibitor; Flomax is an alpha-1 blocker. They act on different targets in the body.
- Time on the market. Proscar was first approved by the FDA in 1992, Flomax in 1997. That gives Proscar roughly 5 more years of real-world use and long-term safety data.
- Who markets them. Proscar is marketed by Organon; Flomax by Sanofi.
- Same drug, more than one brand. Finasteride is sold as Proscar / Propecia — the same active ingredient marketed under different brand names, typically for different approved uses or doses.
What each one treats
PROSCAR, is a 5α-reductase inhibitor, indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to ( 1.1 ): Improve symptoms Reduce the risk of acute urinary retention Reduce the risk of the need for surgery including transurethral resection of the prostate (TURP) and prostatectomy. PROSCAR administered in combination with the alpha-blocker doxazosin is indicated to reduce the risk of symptomatic progression of BPH (a confirmed ≥4 point increase in American Urological Association (AUA) symptom score) ( 1.2 ). Limitations of Use : PROSCAR is not approved for the prevention of prostate cancer ( 1.3 ). 1.1 Monotherapy PROSCAR ® is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to: - Improve symptoms - Reduce the risk of acute urinary retention - Reduce the risk of the need f…
An oral daily capsule used to treat difficulty urinating caused by an enlarged prostate.
How each one works
12.1 Mechanism of Action The development and enlargement of the prostate gland is dependent on the potent androgen, 5α-dihydrotestosterone (DHT). Type II 5α-reductase metabolizes testosterone to DHT in the prostate gland, liver and skin. DHT induces androgenic effects by binding to androgen receptors in the cell nuclei of these organs. Finasteride is a competitive and specific inhibitor of Type II 5α-reductase with which it slowly forms a stable enzyme complex. Turnover from this complex is extremely slow (t ½ ~ 30 days). This has been demonstrated both in vivo and in vitro . Finasteride has no affinity for the androgen receptor. In man, the 5α-reduced steroid metabolites in blood and urine…
An oral daily capsule used to treat difficulty urinating caused by an enlarged prostate.
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Which medicine is right for a given person depends on their diagnosis, other conditions, other medicines, kidney and liver function, pregnancy, and cost or reimbursement — none of which this page knows. Two drugs in the same class are not automatically interchangeable. Never start, stop or switch a prescription medicine on the basis of a web page; that decision belongs to you and your clinician or pharmacist.
How this page is built
The facts on this page are pulled directly from official U.S. FDA datasets — they are not written from memory. Each field below names the dataset it came from, so you can check it yourself.
- FDA Drug Label (openFDA) ↗ Indications, mechanism of action and pharmacologic class
- Drugs@FDA ↗ First FDA approval date and the company holding the application
- FDA Drug Shortage Database ↗ Current US supply / shortage status
Plain-English summaries and drug-class explainers are written and reviewed by Sreepriya Prasannan (MSc Digital Transformation of Life Sciences (Innopharma Education / Griffith College); MSc & BSc Botany). Data is retrieved automatically from the sources above and cross-checked with AI-assisted verification (Anthropic's Claude) — brand and generic names are matched against the exact FDA product record so that a combination product or a different formulation cannot be mistaken for the drug on this page. An editor reviews the result before publication. We describe this in full in our editorial standards and corrections policy. The FDA data on this page was last retrieved on 10 Oct 2026. How every register is built: methodology · fixes we have made: corrections log.