William “Billy” Smyth from Mullingar in Ireland was prescribed a course of the painkiller Nolotil by a Spanish doctor to treat a shoulder pain while on holiday in Torrevieja in February.

Several months later after suffering persistent cold-like symptoms it was discovered that the drug had caused toxic poisoning in his bone marrow.

“He couldn’t shake a common cold and the sore throat he had. The GP checked him out and found his white blood cell count was very low and called an ambulance to take him to emergency straight away,” Smyth’s son Derek told Independent.ie.

The low white cell count led to Smyth developing sepsis and necrotising fasciitis and he underwent emergency surgery in an attempt to remove the affected tissue.

“My father remained in a coma following surgery. He developed multiple organ failure, received a colostomy, kidney dialysis and many life saving measures but on April 17th my father died from septic shock due to the complications developed from taking Nolotil,” said Smyth's son.

The family have now gone public in the belief that other visitors may be in danger if prescribed a drug which is banned in the UK and Ireland and which is known to have a high risk of causing agranulocytosis (lowered white blood cell count).

“We’re obviously upset that the drug was prescribed to him but at the end of the day, the drug is legal in certain countries,” he warned.

“Irish people should be cautious and think twice about what they’re taking. If they even stop for a couple of seconds and think, they could save their lives.”

The Nolotil drug is a brand name for Metamizole, an anti-inflammatory drug used for the treatment of mild pain.

While the drug is available on prescription in Spain, it has never been licensed in the UK, Ireland or the USA.