Do not use Glyceryl Trinitrate 0.4% ointment if the patients:
are allergic to glyceryl trinitrate or to similar medicines
suffer from low blood pressure
suffer from heart or blood vessel disorders
suffer from closed-angle glaucoma
suffer from migraine or recurrent headaches
suffer from increased intracranial pressure or high pressure within your skull
suffer from anaemia
are taking any of the following medicines: sildenafil citrate, tadalafil, vardenafil, medicines for angina or heart pain such as glyceryl trinitrate (GTN), isosorbide dinitrate, amyl or butyl nitrite, medicines for high blood pressure or depression (tricyclic anti-depressants), acetyl cysteine or alteplase