Dutasteride: Adverse effects reported in at least 1% of patients receiving dutasteride and more frequently than with placebo include impotence, decreased libido, ejaculation disorder, and breast disorders (including breast tenderness and enlargement). Ejaculation disorders have been reported more frequently with combined therapy with dutasteride and tamsulosin than with either drug alone.
Tamsulosin: Headache, infection, asthenia, back pain, chest pain, dizziness, somnolence, insomnia, decreased libido, rhinitis, pharyngitis, increased cough, sinusitis, diarrhea, nausea, tooth disorder, abnormal ejaculation, blurred vision.