At least 13 men in Denmark have died in the past 10 years due to complications arising from the use of potency drug Viagra, reported Ekstra Bladet newspaper.
The figure was taken from the official register of the Danish Medicines Agency, which indicated the deaths were caused by a fatal fall in blood pressure as a result of the drug.
'The patients do not receive sufficient blood to their heart muscles, which in turn results in a heart attack,' said Doris Stenver, head of the agency's consumer safety division.
Stenver said, however, that the number is not inordinately high and will not cause the agency to seek a Viagra ban.
'It's a small number in relation to how many men take the medication. But it says something about how important it is that doctors inform the patients of the risks before prescribing the pills because they can have serious side effects for some.'
Stenver said that not all of Viagra's side effects are known yet and what is known may be only 'the tip of the iceberg'.
Viagra's producer, Pfizer, acknowledged that there had been earlier problems caused by the drug when it was taken in combination with certain others.
'The first year of its release there was a row of fatalities in patients that were also taking nitro-glycerine for cardiac spasms. The doctors are aware of that now and the warning is also on the product's inner leaflet,' said Robert Neimanas, Pfizer's head of communications.
Over 40,000 men were prescribed Viagra nationwide in 2005, resulting in sales of DKK 75.5 million for Pfizer.