Media playback is unsupported on your device Media caption Fifa medical officer Professor Jiri Dvorak talks about his research into the use of painkillers at recent World Cups

Fifa's chief medical officer has said the "abuse" of painkillers is putting the careers and long-term health of international footballers in jeopardy.

Dr Jiri Dvorak found that almost 40% of players at the 2010 World Cup were taking pain medication prior to every game.

Ahead of Euro 2012, Dr Dvorak has urged football to wake up to the problem.

He told the BBC that younger players are imitating the seniors and taking painkillers far too frequently.

Fifa's medical team asked team doctors to provide a list of medications that players were taking ahead of each game in the 2010 World Cup.

Previous surveys at international tournaments established that many players were using large numbers of pain killing and non steroidal anti inflammatory drugs (nsaids).

But the results from South Africa 2010, published recently in the British Journal of Sports Medicine , show higher levels of use than ever before.

Thirty-nine percent of all players took a painkilling agent before every game.

There were huge differences between countries with some teams doling out over three medications per player per game.

The case of Ivan Klasnic Croatian striker Ivan Klasnic who now plays for Bolton was the first player in the world to comeback to international football after having a transplant. Klasnic suffered kidney failure while playing for Werder Bremen in Germany in 2007. The cause of Klasnic's kidney loss is still in dispute. He blames team doctors at Werder Bremen saying that they failed to diagnose his problem in time and continued to prescribe painkilling medication to him which can be very damaging to kidneys. The doctors at the club say the problem was caused by genetics and not painkillers. The case is still before the courts in Germany.

Teams from North and South America had the highest reported use of medications per match and per player.

"I think we can use the word abuse - because the dimension is just too much," Dr Dvorak told the BBC.

"Unfortunately, there is the trend to increase the intake of medication. It is something that we have to really take seriously and ask what is behind it?"

Experts say that painkilling medication can be particularly dangerous in professional sport. In high-intensity exercise like football, a player's kidneys are continuously working hard, making them more vulnerable to damage from strong drugs.

Dr Dvorak believes that a major factor in the growing use of painkillers in football is the pressure on team doctors to get injured players back on the pitch quickly.

"The team doctors, most of them they are under pressure between the diagnosis and the appropriate treatment between the pressure to bring the player on the pitch, if they take them too long out they might be out of a job."

Former German international player Jens Nowotny knows from his own experience that there is pressure on everyone.

"It's hard when someone from the club comes and says it's important that you play and the team and the club needs you - it's your decision but the pressure from people around - you can't ignore it.

"And the doctors are under pressure too."

Other scientists agree that the Fifa research is concern.

Dr Hans Geyer, deputy director of the Wada (World Anti-Doping Agency) accredited anti-doping laboratory in Cologne, said: "This is an alarming signal. We have co-operated with Fifa also in this field and we can confirm their data."

I guarantee that many of the athletes I work with are taking nsaids without my knowledge Dr Tanya Hagen, University of Pittsburgh

"What we have seen from the Fifa studies is that often athletes take the pain killers as a preventive. They take them to prevent a pain which may occur, to be totally insensitive.

"The problem is, if you switch off alarm systems that protect your tissues, you can have irreversible destruction of tissue."

Jens Nowotny says players want to play more than anything. To be out injured means someone else is playing and you may not get your place back.

In his view, footballers are willing to do what ever it takes to stay on the pitch.

"It's part of the job - maybe it would be better to take no pain killers, to not ignore the body' s signal to stop, but it is part of the job and we earn a lot of money - it's part of the business."

Other forms of football are also coming to terms with the use of painkilling medications.

In the United States, 12 former NFL players are now suing the league over the use of the powerful anti-inflammatory drug Toradol.

Image caption Painkillers are also causing problems in the NFL

They argue that the medication masked the pain of head injuries and led them to play on and suffer concussions as result.

The players say that sometimes they were lined up in what they termed a 'cattle call' and injected with the drug whether they were injured or not.

Dr Tanya Hagen is from the University of Pittsburgh medical centre. She works with many teams in different sports and has acted as a consultant to the Pittsburgh Steelers in the NFL for 10 years. She says that the easy availability of powerful pain medications contributes to the problem of abuse.

"Even though the use of painkillers is a hot issue for me, I guarantee that many of the athletes I work with are taking nsaids without my knowledge or I'm not even asking them about it.

"Sometimes we don't even see the athletes unless they think it's a severe enough injury to come see the doctor."

And the risks of using nsaids are not just confined to the kidneys and liver. There are also worries over their impact on hearts. Dr Stuart Warden from the University of Indiana is an expert in the use of these drugs by athletes.

"There is an elevated risk of cardio vascular side-effects with almost all nsaids and the risk increases with duration of use. It is best to limit nsaid use to when it is indicated - such as the treatment of acute pain and inflammation.

However, cardio vascular side effect risk does depend on the presence of other risk factors and the type nsaid being taken. "

As well as concerns about senior players using pain medications at tournaments like the upcoming Euro 2012, Dr Dvorak is increasingly worried about younger players.

"Football has to wake up because the youngsters are mimicking the older ones. We have nsaid abuse in the under-17 age competitions by something like 16-19% of players. This for me is even more alarming."

"We have to change the attitude. It is a cultural phenomenon because the medications are so easily accessible."