[6] Common side effects include dizziness, headache, insomnia, nausea, blurry vision, and sexual problems.

[9][6] Other side effects may include feeling lightheaded with standing due to changes in blood pressure, and angioedema.

[16] The results of the CombAT (combination of dutasteride [Avodart] and tamsulosin [Duodart]) trial in 2008 demonstrated that treatment with the combination of dutasteride and tamsulosin provides greater symptom benefits compared to monotherapy with either agent alone for treatment of benign prostatic hyperplasia.

[25] When alpha 1 receptors in the bladder neck, prostate, ureter, and urethra are blocked, a relaxation in smooth muscle tissue results.

[16] This mechanism decreases resistance to urinary flow, reduces discomfort associated with BPH, and facilitates passage of kidney stones.

Tamsulosin hydrochloride extended-release capsules are marketed under the trade names Urimax 0.4 (India),Tamlocept 0.4 (India), Flomax, Flomaxtra, Contiflo XL, bestflo, Mecir LP (France), Urimax, Pamsvax, and Pradif,[29] although generic, unmodified-release capsules are still approved and marketed in many countries (such as Canada).

[31] In Egypt,[32] Italy, Russia and Iceland, it is marketed under the trade name Omnic by Astellas Pharma Europe.