Flomax and Viagra for BPH Treatment

  • Medical Reviewer: John P. Cunha, DO, FACOEP
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

Flomax and Viagra for BPH Quick Comparison

What is Flomax? What is Viagra?

Flomax (tamsulosin) is an oral drug prescribed to treat men who are having difficulty urinating because of an enlarged prostate gland due to benign prostatic hyperplasia (BPH). Difficulty urinating is caused only in part by the enlarged prostate. The other cause of the difficulty is the muscle cells tightening around the bladder outlet. Flomax helps the muscles relax, which results in a decrease in obstruction to the flow of urine.

Viagra (sildenafil) is used for treating impotence (or erectile dysfunction, ED, the inability to attain or maintain a penile erection). It is in a class of drugs called phosphodiesterase inhibitors (PDE-5 inhibitors) that also includes tadalafil (Cialis), vardenafil (Levitra, Staxyn ODT), and avanafil (Stendra). It works by increasing blood flow to the penis, enabling a man to get and keep an erection.

What are the side effects of Flomax and Viagra?

Flomax side effects

The most common adverse effects of Flomax include:

Other side effects include:

More serious side effects that have been observed in male patients during treatment with Flomax include:

Viagra side effects

Approximately 15% of males taking Viagra experience side effects.

The most common side effects include:

Benign Prostatic Hyperplasia Quiz: Test Your BPH IQ

What is the dosage of Flomax and Viagra?

Flomax dosage instructions

  • The recommended starting dose is 0.4 once daily about 30 minutes after the same mealtime each day.
  • When taken on an empty stomach, more of the medication is absorbed.
  • This could cause a greater effect and potentially a drop in blood pressure.
  • The dose may be increased to 0.8 mg once daily after 2 to 4 weeks if the response is not adequate.
  • The capsules should not be crushed, chewed, or opened.

Viagra dosage instructions

  • The usual recommended dose is 25 to 100 mg 1 hour before sexual activity.
  • The maximum dose is 100 mg daily.
  • The elderly (over 65 years of age) should start at 25 mg before sexual activity.
  • Sildenafil is rapidly absorbed. Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When sildenafil is taken with a high fat meal, the rate of absorption is reduced, with an average delay in the time to maximal concentration of 1 hour.

What are the drug interactions of Flomax and Viagra?

Flomax drug interactions

The elimination of Flomax from the body may be reduced by:

Reduced elimination may lead to increased side effects of Flomax. PDE-5 inhibitors (for example, vardenafil [Levitra, Staxyn], Adcirca, sildenafil [Viagra, Revatio], tadalafil [Cialis]) add to the blood pressure lowering effects of Flomax and may result in severe blood pressure reduction.

Viagra drug interactions

Viagra increases the effects of the blood pressure lowering medications. It also increases the blood pressure lowering effects of nitrates, for example, isosorbide dinitrate (Isordil), isosorbide mononitrate (Imdur, Ismo, Monoket), nitroglycerin (Nitro-Dur, Transderm-Nitro) that are used primarily for treating angina. Patients taking nitrates should not receive Viagra.

Cimetidine (Tagamet), erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), atazanavir (Reyataz), and mibefradil (Posicor) can cause marked increases in the amount of Viagra in the body. Patients taking these medications should be observed carefully if sildenafil is used.

Patients should not combine Viagra with other PDE5 inhibitors (for example, vardenafil [Levitra], tadalafil [Cialis]).

It is expected that rifampin will decrease blood levels of Viagra and probably reduce its effectiveness.

REFERENCE: FDA Prescribing Information for Flomax and Viagra.

Summary

Flomax (brand name tamsulosin) is a medication doctors prescribe to males who have an enlarged prostate gland and who are having difficulty urinating due to a condition called benign prostatic hyperplasia (BPH). Flomax blocks chemicals in the muscle cells of the penis to relax, which results in the ability to urinate. Viagra (brand name sildenafil) is a medication doctors prescribe to men who are having problems getting and sustaining an erection (erectile dysfunction, ED, impotence). Viagra works by increasing blood flow to the penis, which allows for a man to get and keep an erection.

Common side effects of Flomax include:


Less common side effect include:
Flomax does have serious side effects that include a prolonged erection, intraoperative floppy iris syndrome (an eye problem), and orthostatic hypotension. Click here for dosage and drug interactions for Flomax.

Common side effects of Viagra include:
Click here for dosage and drug interaction information for Viagra.

REFERENCES: FDA Prescribing Information for Flomax and Viagra.

Treatment & Diagnosis

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Reviewed on 9/19/2017
References
REFERENCE: FDA Prescribing Information for Flomax and Viagra.

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