The Queensland Rugby League will investigate a claim some players took a home-made party drug amid extented partying before last week's State of Origin third match loss to New South Wales.
Queensland had already sealed a series victory and lost 28-16 at Suncorp Stadium.
Queensland's boss Ross Livermore says there'll be an investigation after The Australian newspaper reported allegations some players mixed a prescription sleeping drug Stilnox with an energy drink.
The combination is said to produce a similar effect to party drugs, while allowing players to avoid testing positive as Stilnox is not on the World Anti-Doping Agency's prohibited drugs list.
Queensland has also been accused of other poor preparation for last week's loss after extended drinking sessions while in camp - including partying by some players at Surfers Pardise the day before the match.