Common side effects include dizziness, headache, sleeplessness, nausea, [[blurry vision]], and sexual problems.<ref name=BNF76/><ref name=AHFS2018/> Other side effects may include [[feeling lightheaded with standing]] due to changes in blood pressure ([[Orthostatic hypotension|hypotension]]), and [[angioedema]].<ref name=BNF76/> Tamsulosin is an [[alpha blocker]] and works by relaxing muscles in the prostate.<ref>{{cite book | vauthors = Hutchison LC, Sleeper RB |title=Fundamentals of Geriatric Pharmacotherapy: An Evidence-Based Approach |date=2010 |publisher=ASHP |isbn=9781585283057 |page=209 |url=https://books.google.com/books?id=fUtOugU_KeIC&pg=PA209 |language=en}}</ref> Specifically it is an [[alpha-1 adrenergic receptor|α<sub>1</sub> adrenergic receptor]] blocker.<ref name=AHFS2018/>
