As with every PDE5 inhibitor, tadalafil is absolutely contraindicated with nitrate medications for angina pectoris secondary to the potentiated hypotensive effect the drugs can have together. Because of the longer half-life, treatment with nitrate medications must be deferred for at least 48 hours after ingestion of tadalafil, compared with 24 hours for sildenafil (Viagra) and [...]

read more from " Safety and drug interactions "