Munster prop James Cronin has been handed a one-month ban for an unintentional anti-doping violation after a mix-up in a pharmacy led to him receiving the wrong medication.
The Ireland player failed the doping test after Munster's Champions Cup home game against Racing 92 in November.
The 29-year-old tested positive for prednisolone and prednisone.
A disciplinary ruling found that the breach was due to a dispensing error by the pharmacy.
The ruling stated that Cronin, who has three Ireland caps, had co-operated fully with a subsequent investigation of the case by European Professional Club Rugby and the matter was referred for decision to an independent judicial officer Antony Davies.
"Prior to the match against Racing 92, Cronin had been unwell and had been prescribed antibiotics, however, the pharmacy dispensed medication to him which was intended for another customer," read a statement from Davies.
"The judicial officer accepted evidence that the banned substances in the player's sample were due to a dispensing error by the pharmacy and that the anti-doping violation was entirely unintentional.
"Although the judicial officer found that there was no significant fault on behalf of the player, and that there were clear and compelling mitigating factors, he determined that the player had to bear some responsibility for what was in his sample.
"It was therefore decided that Cronin will be ineligible for a one-month period from 15 April 2020 until 16 May 2020."
World Rugby, Sport Ireland and the World Anti-Doping Authority each has the right to appeal against the verdict.
Munster chief executive Ian Flanagan said the situation had been "an extremely challenging time" for Cronin.
"Clearly the sanction is reflective of the strong mitigating factors in this case, and we look forward to James' return to action," added the Munster chief executive.
Like all sport, rugby union has been halted because of coronavirus and it is not clear when the game will resume.