Allergy to class/drug
Pericardial tamponade
Severe anemia
Sildenafil use within the past 24 hours or tadalafil within the past 48 hours
Methemoglobinemia
Caution in hypotension
Nitroglycerin
Nitroprusside
Adenosine
Atenolol
Nifedipine
Dobutamine
Hydralazine
Carvedilol