Allergic reaction in patients w/ history of sulfonamide allergy. Syncope. Sit or lie down at 1st signs of orthostatic hypotension eg, dizziness, weakness. Perform digital rectal exam & determine PSA before treatment & at regular intervals afterwards. Intraoperative floppy iris syndrome during cataract & glaucoma surgery. Not recommended to initiate therapy in patients whom cataract or glaucoma surgery is scheduled. Not to be given in combination w/ strong CYP3A4 inhibitors in patients w/ poor CYP2D6 phenotype metaboliser. May affect ability to drive & use machines. Severe renal impairment (CrCl <10 mL/min). Childn <18 yr.