Determine potential underlying causes of erectile dysfunction before considering pharmacological treatment. Consider CV status of patients before treatment initiation. Patients w/ pre-existing CV risk factors; anatomical deformation of the penis (eg, angulation, cavernosal fibrosis, Peyronie's disease) or risk factors for priapism (eg, sickle cell anaemia, multiple myeloma, leukaemia); rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption. Discontinue in case of sudden visual defect. Not recommended w/ doxazosin. Caution when co-administered w/ potent CYP3A4 inhibitors (ritonavir, saquinavir, ketoconazole, itraconazole, erythromycin). Do not co-administer w/ other PDE5 inhibitors or other treatments for erectile dysfunction. Not recommended in patients w/ severe renal & hepatic impairment. Not indicated in women. No relevant use in paed population.