Monaghan cyclist Conor Murphy has tested positive for the banned substance pseudoephedrine, according to Cycle Ireland.
The 20-year-old had tests carried out by the UK Sports Council's Drug Free Sport Unit at the Tour of Ulster at the beginning of this month, where he finished seventh overall.
"It is imperative that all athletes from cyling and other sports show great diligence when taking medicines. Ignorance is no excuse for contravening the clearly stated anti-doping regulations of the national governing bodies," was Cycle Ireland's chief executive Stuart Hallam's response to the matter.
If found guilty Murphy could get banned for up to six months at a disciplinary hearing next month.