Flomax and Viagra for Benign Prostatic Hyperplasia Treatment

Medically Reviewed on 6/2/2022

Flomax vs. Viagra

What is Flomax? What is Viagra?

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:

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


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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). 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 headache, dizziness, hay fever, anemia, abnormal taste in the mouth, weakness, nausea, and vomiting. Common side effects of Viagra include flushing, muscle pain (myalgia), nausea, back pain, problems with vision, indigestion, headache, rash, nasal congestion, and dizziness.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 6/2/2022
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