Johannesburg - Footballers across the globe have been warned of the long-term effects of painkillers following the release of information gathered over the past 14 years.

FIFA chief medical officer, Professor Jiri Dvorak, was part of the team tasked with collecting information on the various medications players took prior to matches, including those at the 2010 Soccer World Cup in South Africa.

It has now be confirmed around 39% of all players at the tournament were on one sort of non steroidal anti-inflammatory drug or another.

Dvorak has now moved to warn players of the dangerous effects of 'abusing' painkillers, telling FIFA's official website: "Since 1998 we've collected data about the intake of medication for all players at every FIFA tournament, which roughly equates to 55 competitions from U-17 tournaments to senior club and national team competitions.

"The results are striking. Even at U-17 level, between 20-25 percent of players are taking anti-inflammatory drugs and painkillers and this increases to senior World Cup levels, which sees 30-35 per cent of usage. When we combine that with the usage of non steroidal anti-inflammatory drugs, it equates to about half of the players.

"Some of the players are probably taking this medication without a prescription from the team doctors, they're just taking them and then telling the doctor. Others are taking them under prescription from the doctors as they're suffering some kind of pain or discomfort.

"But other players could also be using these painkillers in advance to reduce the pain caused by potential discomfort during a match. That could be dangerous. By masking symptoms through painkillers, you could be covering something which could be important in the long run.

"First of all, we need to raise awareness with the physicians responsible for the teams in all member associations so they think twice before prescribing this type of medication.

"Every medication you take has potential side effects, such as the building of blood content, but it could also have a negative effect on the function of the liver and kidneys, particularly if a particular medication has been taken for a long time. Some of the medications can also irritate the gastro-intestinal tract which can lead to internal bleeding of different magnitudes.