Silodosin (Rapaflo and others)

How Medicare covers it

Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.

What it treats

The signs and symptoms of benign prostatic hyperplasia (BPH) — an enlarged prostate. It is not for the treatment of hypertension (high blood pressure).

What it is for, in depth

Rapaflo (silodosin) treats the signs and symptoms of benign prostatic hyperplasia (BPH) — a non-cancer enlarged prostate in men that squeezes the urethra and makes urination hard. Symptoms it addresses include difficulty urinating, painful urination, weak flow, and increased urinary frequency or urgency. It is prescribed for men with BPH after an exam to rule out prostate cancer, which can cause similar symptoms. In the treatment path, it is a daily symptom-relief medicine: it relaxes the prostate and bladder neck so urine flows more easily, it controls symptoms but does not shrink the prostate or cure BPH, and it is not a blood pressure medicine even though it is an alpha-blocker. Forms and strengths: capsules of 4 mg and 8 mg — 8 mg once daily with a meal is the usual dose, and 4 mg once daily with a meal is the dose for moderate kidney impairment.

How it works

Silodosin (Rapaflo) is a selective alpha-1 blocker. It blocks alpha-1 receptors in the prostate, bladder base, bladder neck, prostatic capsule, and prostatic urethra. Blocking these receptors relaxes the smooth muscle in those tissues, which improves urine flow and reduces BPH symptoms.

How it is taken

Taken by mouth as a capsule, once a day with a meal — do not take it on an empty stomach. The usual dose is 8 mg once daily with a meal. For people with moderate kidney impairment (creatinine clearance 30–50 mL/min), the dose is 4 mg once daily with a meal. Take it at about the same time every day and keep taking it even if you feel well.

Common side effects

The most common side effects (more than 2%) are retrograde ejaculation (orgasm with little or no semen), dizziness, diarrhea, orthostatic hypotension (blood pressure dropping when standing), headache, nasopharyngitis (common-cold symptoms), and nasal congestion (stuffy nose).

Serious warnings

This label has no boxed warning. Low blood pressure on standing (postural hypotension), with or without symptoms such as dizziness, may develop when you start Rapaflo — get up slowly and sit or lie down if you feel dizzy or faint. Before starting, patients thought to have BPH should be examined to rule out prostate cancer. Tell your eye doctor you take Rapaflo if you plan cataract surgery, because of the possibility of Intraoperative Floppy Iris Syndrome (IFIS) during the surgery. It must not be used in severe kidney impairment, severe liver impairment, or with strong CYP3A4 inhibitors (see interactions).

Who should be careful

People with moderate kidney impairment need the lower 4 mg dose, and people with severe kidney impairment (creatinine clearance under 30 mL/min) or severe liver impairment (Child-Pugh score over 10) must not take it. People with low blood pressure should be careful about dizziness and fainting when starting. Anyone planning cataract surgery should tell their ophthalmologist. Silodosin is for use in men; women should not take it, especially if pregnant or breast-feeding.

Major interactions

Strong CYP3A4 inhibitors such as ketoconazole, clarithromycin, itraconazole, and ritonavir must not be used with silodosin — this is a contraindication. Strong P-glycoprotein inhibitors such as cyclosporine are not recommended, because they may raise silodosin levels. Do not combine it with other alpha-blockers. Using PDE5 inhibitors (ED medicines) together with alpha-blockers including Rapaflo can potentially cause symptomatic low blood pressure.

Cost and saving notes

Generic silodosin is available, and asking for the generic instead of brand-name Rapaflo can lower what you pay. This drug is covered under Medicare Part D. If your plan's tier makes the copay hard to afford, you can ask your plan for a tier exception to get it at a lower tier price. If you qualify for Extra Help (the Part D Low-Income Subsidy), your copays will be much lower. In 2027, Part D has a $2,400 yearly cap on what you pay out of pocket for covered drugs, and the Medicare Prescription Payment Plan lets you spread those out-of-pocket costs into monthly payments during the year instead of paying them all at the pharmacy counter.

Why it is in its tier

Silodosin (Rapaflo and others) sits on Tier 3 in 62.28% of the plans that list it (2328 of 3738 listing plans). Tier 3 is the preferred brand tier — mid-level copays or coinsurance. The data-visible drivers: It is a generic product, and the CMS dashboard puts its average Part D spending at about $299 per beneficiary for 2024 — a relatively low-cost drug, which matches where plans place it. It is listed by 68.03% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• RAPAFLO (SILODOSIN) CAPSULE [PHYSICIANS TOTAL CARE, INC.] — DailyMed
• MedlinePlus — National Library of Medicine
• MedlinePlus — Silodosin

What official patient guides say

Silodosin comes as a capsule to take by mouth (the Rapaflo capsule form in this package). MedlinePlus says to take it with food once a day — do not take silodosin on an empty stomach — and to take it at around the same time every day. Take it exactly as directed — do not take more or less of it or take it more often than your doctor prescribed. Silodosin controls the symptoms of an enlarged prostate (BPH) but does not cure it. Continue to take it even if you feel well, and do not stop taking it without talking to your doctor. If you forget a dose, take the missed dose with a meal as soon as you remember it. If it is almost time for the next dose, skip the missed dose and go back to your regular schedule. Do not take a double dose to make up for a missed one. Keep the capsules in the container they came in, tightly closed and out of reach of children. Store them at room temperature, away from extra heat and moisture, and not in the bathroom. Do not flush leftover medicine. Ask your pharmacist about a medicine take-back program.

Source: MedlinePlus — Silodosin

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

Without insurance, the cash benchmark is 0.28121 per unit (SILODOSIN 4 MG CAPSULE) — about nan for 30 units. NADAC benchmark — the average price pharmacies pay (CMS, as of 2026-11-04). Pharmacy shelf prices vary.

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-08

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 3,738 list Silodosin (Rapaflo and others) — 68.0% of plans. Most of those plans put it on Tier 3: 2,328 plans, 62.3% of the plans that list it. Other plans place it on Tier 4 (1,040 plans), Tier 2 (315 plans) or Tier 1 (55 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 4; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 4; Aetna Medicare Value Plus (PPO) puts it on Tier 4. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.