There have been no drug interaction studies for Dutasteride + Tamsulosin HCl.
The following statement reflect information available for the individual components.
Dutasteride: In contrast, no decrease in clearance was seen Amlodipine, another calcium channel antagonist, was co-administered with Dutasteride. A decrease in clearance and subsequent increase in exposure to Dutasteride, in the presence of CYP3A4 inhibitors, are unlikely to be clinically significant due to the wide margin of safety (up to 10-times the recommended dose has been given to patients for up to six months); therefore, no dose adjustment is necessary.