Some of my patients with ED taking tadalafil also have ischemic heart disease. Can I prescribe PRN nitrate therapy in case they have chest pain?

No. All PDE5 inhibitor therapy including tadalafil  are contraindicated in men taking any form  of organic nitrates including sublingual and  long-acting nitroglycerin. PDE5 inhibitors  potentiate the hypotensive effect of nitrates.  Nitrate therapy, even if PRN, should not be  prescribed and patients should be instructed  to discard any leftover nitroglycerin tablets  while on PDE5 inhibitor therapy. Patients  with ischemic heart disease who wish to take  a PDE5 inhibitor for the treatment of their ED  should be counseled that in case they have  chest pain they should seek immediate medical  care, they should not take nitroglycerin,  and they should inform the health care provider  that they are on a PDE5 inhibitor, and  when they last took it. Though nitrates are  highly effective in relieving pain associated  with myocardial ischemia, they do not alter  long-term survival [63–65].