Rapaflo (Silodosin) - Oral

What Is Rapaflo?

Rapaflo (silodosin) is a treatment option for benign prostatic hyperplasia (BPH). It's a member of the alpha-1 adrenergic receptor antagonist medication class, which is also simply called the alpha-blocker class.

It works by attaching to the alpha-1 adrenergic receptors (binding sites). These receptors are located in different parts of the prostate. By binding to these receptors, silodosin relaxes the smooth muscle in the prostate. This relaxation relieves BPH symptoms and improves urine flow.

Silodosin is available as a prescription capsule. The Food and Drug Administration (FDA) hasn't assigned any black box warnings to this medication.

Drug Facts

Generic Name: Silodosin

Brand Name(s): Rapaflo

Drug Availability: Prescription

Therapeutic Classification: Alpha-blocker

Available Generically: Yes

Controlled Substance: No

Administration Route: Oral (by mouth)

Active Ingredient: Silodosin

Dosage Form(s): Capsule

What Is Rapaflo Used For?

Rapaflo (silodosin) is a treatment option for benign prostatic hyperplasia (BPH). BPH is an enlarged prostate medical condition.

This condition is common in adults assigned male at birth who are older than 50. As this population gets older, the prostate may increase in size. This enlarged prostate surrounds and squeezes the urethra, a tube through the penis that gets rid of urine.

This squeezed tube may result in the following BPH symptoms:

  • Weak or slow urine stream
  • Frequent or urgent need to urinate
  • Small amounts of blood in your urine
Rapaflo (Silodosin) Drug Information: A Person and their prostate

Verywell / Zoe Hansen

How to Take Rapaflo

Rapaflo (silodosin) is taken by mouth once daily with a meal.

If you have swallowing difficulties, consider the following general directions.

  1. Gently pull the silodosin capsule apart.
  2. Sprinkle the capsule's contents (powder) onto a tablespoon of soft applesauce. Use all of the capsule's contents. Don't try to save any of the capsule's contents for future use. Also, make sure the applesauce isn't hot.
  3. Swallow the mixture—without chewing—within five minutes. The combination should not be saved for future use.
  4. Drink an 8-ounce (oz) glass of cool water to swallow any powder that's still stuck in your mouth.

Storage

Once you pick up Rapaflo (silodosin) from the pharmacy, store the medication between 59 degrees to 86 degrees Fahrenheit (F). Room temperature should be within this range. Don't expose this medication to light or moisture.

To be safe, you may also place silodosin in a locked cabinet or closet to keep your medication out of reach of children and pets.

If you plan to travel with silodosin, get familiar with your final destination's regulations. In general, be sure to make a copy of your silodosin prescription. Keep your medication in its original container from your pharmacy with your name on the label. If you have any questions about traveling with your medicine, ask your pharmacist or healthcare provider.

Visit the FDA's website to know where and how to discard all unused and expired drugs. You can also find disposal boxes in your area. Ask your pharmacist or healthcare provider if you have any questions about the best ways to dispose of your medications.

Off-Label Uses

There's some evidence to support alpha-blockers—like silodosin—in treating kidney stones that get stuck in the ureters (tubes that move urine from the kidneys to the bladder).

How Long Does Rapaflo Take to Work?

You may notice an improvement in your urine flow within the first day of taking Rapaflo (silodosin).

What Are the Side Effects of Rapaflo?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Common side effects of Rapaflo (silodosin) may include:

Severe Side Effects

Contact your healthcare provider right away if you develop any signs of a severe reaction. Call 911 if your symptoms feel life-threatening.

Serious side effects and their symptoms include:

  • Severe allergic reaction: If you have a severe allergic reaction to silodosin, symptoms may include breathing difficulties, hives, and swelling.
  • Orthostatic hypotension: If you have orthostatic hypotension, you may experience low blood pressure with posture (positional) changes. Your blood pressure can become too low and lead to symptoms of dizziness and fainting.
  • Intraoperative floppy iris syndrome (IFIS): Alpha-blockers—like silodosin—may raise your likelihood of IFIS during cataract surgery. In IFIS, the iris (part of the eye that's responsible for pupil size) may decrease the pupil size or slip out of place. The iris may also billow (rise and roll) like the ocean.

Long-Term Side Effects

The risk of IFIS is still possible after stopping Rapaflo (silodosin). Make sure to tell your healthcare provider about your current or previous use of silodosin before cataract surgery.

Report Side Effects

Rapaflo may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Rapaflo Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (capsules):
    • For benign prostatic hyperplasia (BPH):
      • Adults—8 milligrams (mg) once a day.
      • Children—Use is not recommended.

Modifications

The following modifications (changes) should be kept in mind when using Rapaflo (silodosin):

Severe allergic reaction: If you have a severe allergic reaction to silodosin or any other ingredients in Rapaflo, your healthcare provider will choose another treatment option.

Pregnancy: Rapaflo isn't typically indicated for people assigned female at birth.

Breastfeeding: Rapaflo isn't usually indicated for people assigned female at birth.

Older adults over 65: Compared to younger adults, some older adults may be more likely to experience low blood pressure with postural (positional) changes. Otherwise, there were no other safety or effectiveness differences between these age groups.

Children: There is limited safety and effectiveness information about Rapaflo in children.

Kidney problems: If you have moderate kidney impairment, your healthcare provider may lower your daily Rapaflo dose to 4 milligrams (mg). If you have severe kidney impairment, Rapaflo isn't recommended.

Liver problems: If you have severe liver impairment, avoid Rapaflo.

Prostate cancer: Prostate cancer and BPH (enlarged prostate) may have similar symptoms. Before starting you on Rapaflo, your healthcare provider will want to rule out prostate cancer.

People with swallowing difficulties: The Rapaflo capsule can be gently pulled apart if you have trouble swallowing capsules. Then, the capsule's contents (powder) can be immediately taken with non-hot applesauce—without chewing.

Missed Dose

If you accidentally forgot your Rapaflo (silodosin) dose, take it as soon as you remember. If it's already close to your next scheduled dose, however, then skip the missed dose and take the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.

Try to find ways to help yourself remember to routinely take your medication that works for you. If you miss too many doses, Rapaflo might be less effective.

Overdose: What Happens If I Take Too Much Rapaflo?

The symptoms of a suspected overdose of Rapaflo (silodosin) may include:

  • Dizziness or lightheadedness
  • Fainting
  • Vision changes

If you think you're experiencing an overdose or life-threatening symptoms, seek immediate medical attention.

What Happens If I Overdose on Rapaflo?

If you think you or someone else may have overdosed on Rapaflo, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Rapaflo, call 911 immediately.

Precautions

Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits for any unwanted effects that may be caused by this medicine.

Do not use this medicine if you are also taking clarithromycin (Biaxin®), ketoconazole (Nizoral®), itraconazole (Sporanox®), or ritonavir (Norvir®). Using these medicines together may cause serious unwanted effects.

Dizziness, lightheadedness, or fainting may occur after you take this medicine, especially when you get up from a lying or sitting position. Getting up slowly may help lessen this problem. If you feel dizzy, lie down so you do not faint. Then sit for a few moments before standing to prevent the dizziness from returning.

This medicine may cause some people to become dizzy or less alert than they are normally. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

Benign prostatic hyperplasia can have the same symptoms as prostate cancer. They may also often occur together. Your doctor may test for the presence of the cancer before you start using this medicine.

Tell your eye doctor (ophthalmologist) that you have used or are using this medicine before cataract surgery or any other eye procedure. This medicine may cause a serious eye problem called Intraoperative Floppy Iris Syndrome (IFIS).

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Rapaflo?

Before taking Rapaflo (silodosin), talk with your healthcare provider if any of the following applies to you:

  • Severe allergic reaction: If you have a severe allergic reaction to Rapaflo or any of its ingredients, Rapaflo isn't a viable option for you.
  • Pregnant or nursing parents: Rapflo isn't typically indicated for people assigned female at birth.
  • Older adults over 65: Compared to younger adults, some older adults may have a higher likelihood of low blood pressure with posture (positional) changes.
  • Children: There is limited effectiveness and safety data about Rapaflo in children.
  • Kidney or liver problems: If you have severe kidney or liver impairment, Rapaflo isn't recommended.
  • Prostate cancer: Prostate cancer and BPH (enlarged prostate) may have similar symptoms. Therefore, your healthcare provider will rule out prostate cancer before starting you on Rapaflo.
  • Intraoperative floppy iris syndrome (IFIS): Rapaflo may increase your IFIS risk during cataract surgery. Before cataract surgery, notify your healthcare provider about your current or previous use of Rapaflo.

What Other Medications Interact With Rapaflo?

Use caution when taking Rapaflo (silodosin) with the following medications:

  • Alpha-blockers: Rapaflo hasn't been studied with other alpha-blockers. Combining Rapaflo with other alpha-blockers—like Flomax (tamsulosin)—isn't recommended.
  • Phosphodiesterase-5 (PDE5) inhibitors: Combining PDE5 inhibitors—like Cialis (tadalafil)—is linked with more side effects, such as low blood pressure from posture (positional) changes.
  • Blood pressure medications: Taking Rapaflo with blood pressure medications may raise the likelihood of side effects, such as dizziness and low blood pressure from posture changes.
  • CYP3A4 inhibitors: CYP3A4 is a protein in the liver that's responsible for breaking down medications, such as Rapaflo. Strong CYP3A4-inhibiting medications—like the itraconazole antifungal—prevents CYP3A4 from working as well. With a build-up of Rapaflo in the body, there's a higher chance of side effects. As a result, combining Rapaflo with strong CYP3A4-inhibiting medications isn't recommended.
  • P-glycoprotein (P-gp) inhibitors: P-gp is a protein that helps move medications—like Rapaflo—around in your body. P-gp inhibitors—like cyclosporine that suppresses the immune system (the body's defense system)—may increase Rapaflo levels in the body, which also raise the risk of side effects.

For more detailed information about medication interactions with Rapaflo, talk with your pharmacist or healthcare provider.

And be sure to talk with your healthcare provider about all prescription and nonprescription medications, vitamins, supplements, and herbal products you are taking or planning to take.

What Medications Are Similar?

There are different medications used to treat BPH. Since Rapaflo (silodosin) is an alpha-blocker, the following medications are most similar to silodosin.

  • Doxazosin
  • Flomax (tamsulosin)
  • Uroxatral (alfuzosin)
  • Terazosin

In general, all BPH medications—including alpha-blockers—are effective at relieving BPH symptoms. Compared to non-specific alpha-blockers (e.g., doxazosin and terazosin), however, silodosin, tamsulosin, and alfuzosin are linked to a lower risk of low blood pressure with posture changes.

Alpha-blockers—like silodosin and tamsulosin, on the other hand, are more specific to the alpha 1a receptor (binding site). This specificity, however, is linked to a higher chance of sexual-related side effects, such as ejaculation dysfunction.

Since all of these medications are alpha-blockers, they're not typically recommended to be used together.

Frequently Asked Questions

  • Where is Rapaflo available?

    Rapaflo is available as a prescription from your healthcare provider. Your local retail pharmacy likely carries this medication. If necessary, the pharmacy staff may need to order it for you.

  • How much does Rapaflo cost?

    Rapaflo is available in a generic version. This may help you save some money.

  • Why do I need to take Rapaflo with food?

    Taking Rapaflo with food may lower your risk of side effects.

  • Are ejaculation problems with Rapaflo permanent?

    Ejaculation dysfunction is a possible side effect of Rapaflo. In general, the side effect will go away after you stop taking the medication. Before you discontinue Rapaflo, however, talk with your healthcare provider first.

  • Will I need other medications in addition to Rapaflo?

    While Rapaflo can be taken by itself, some people will take Rapaflo in combination with other medications—like 5-alpha reductase inhibitors (5-ARIs). Proscar (finasteride) is an example 5-ARI.


    Compared to alpha-blockers, 5-ARIs may take longer to work. It takes time to decrease dihydrotestosterone (DHT) levels that are affecting prostate size.

How Can I Stay Healthy While Taking Rapaflo?

If you're taking Rapaflo, chances are BPH (enlarged prostate) has been negatively affecting your quality of life. You may have tried different approaches or treatments. While living with BPH does have its challenges, there are ways to help improve your quality of life. Refer below for some general tips to support your health:

  • Take BPH-related medications as recommended by your healthcare provider.
  • Achieve a healthy weight to prevent high hormone levels that encourage a large prostate size.
  • Have a healthy diet and exercise routine to help with healthy weight goals.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. Silodosin.

  2. Food and Drug Administration. Rapaflo label.

  3. MedlinePlus. Enlarged prostate.

  4. MedlinePlus. Urethral disorders.

  5. Wang CJ, Tsai PC, Chang CH. Efficacy of silodosin in expulsive therapy for distal ureteral stones: a randomized double-blinded controlled trial. Urology Journal. 2016;13(3):2666-2671. doi:10.22037/uj.v13i3.3266

  6. ScienceDirect. Intraoperative floppy iris syndrome.

  7. ScienceDirect. CYP3A4.

  8. ScienceDirect. P-glycoprotein.

  9. American Urological Association. Management of benign prostatic hyperplasia/lower urinary tract symptoms: AUA guideline 2021.

  10. Food and Drug Administration. Orange book: approved drug products with therapeutic equivalence evaluations.

  11. Urology Care Foundation. Benign prostatic hyperplasia (BPH).

By Ross Phan, PharmD, BCACP, BCGP, BCPS
Ross is a writer for Verywell with years of experience practicing pharmacy in various settings. She is also a board-certified clinical pharmacist and the founder of Off Script Consults.