A US federal advisory board voted on Tuesday to recommend a ban on painkillers Percocet and Vicodin because of their suspected harmful effect on liver.

Percocet and Vicodin are two of the most-frequently prescribed painkillers across the world. These drugs combine a narcotic with acetaminophen which is the primary ingredient in most popular over-the-counter painkillers and anti-pyretics like Tylenol and Excedrin. However overdose of acetaminophen has been known to cause liver damage and a prolonged use of the ingredient may have a harmful effect on the liver. The advisory panel noted that patients who take acetaminophen over a long period of time may need increasingly bigger doses to achieve the same effect, thus putting their liver at risk.

The federal advisory panel voted 20-17 in favor of recommending a ban on painkillers which combine Acetaminophen with narcotics. In the US at least seven other prescription painkillers are based on such a combination. While Vicodin and similar generic products are alone prescribed more than 100 million times in the country, a report estimates that American consumers bought 28 billion doses of acetaminophen in 2005.

The Food and Drug Administration is however not bound to follow the recommendations of its advisory panels.