Sildenafil has an excellent safety record in its clinical trials but there have been reports of deaths associated with its usage now that it is in widespread clinical use. Many of these deaths are clearly unrelated to the drug and some may be related to usage where there are clear contradictions to its use. Some deaths may occur because the patients are at risk from cardiac problems but there remains an occasional unexplained death. There is no evidence at present to suggest that sildenafil is a specific causative factor and the research so far has failed to support it as such.