Dear patient, Thanks for your query. Both medications tend to be safe on the long term. In terms of the sildenafil, vision changes, particularly abnormal perception of colors, could be a serious side effect; dapoxetine can be associated rarely with abnormal rhythms of the heart but this is quite rare. What I always tell patients taking sildenafil is to be aware if they ever have an episode of chest pain requiring medical care, that administration of nitrates such as nitroglycerin can really drop the blood presssure if you have recently taken sildenafil, so disclose all the medcations to treating providers. Hope that helps, wish you the best, Dr Brenes-Salazar MD Mayo Clinic Cardiology