Munster prop James Cronin has been banned for one month for an "unintentional anti-doping violation".
Cronin tested positive for the banned substances prednisolone and prednisone without a medical exemption following the Heineken Champions Cup match against Racing on 23 November.
The EPCR established that this positive test was due to a mix-up in prescriptions, which saw Cronin dispensed another pharmacy customer's medication after feeling unwell and visiting the doctor in advance of the game.
Munster chief executive Ian Flanagan described the situation as "an extremely challenging time" for the the 29-year-old Ireland international and said the province were looking forward to Cronin's return to action.
The independent judicial officer, Antony Davies of England, 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.
Therefore, Cronin will be ineligible for a one-month period from 15 April until 16 May.
Cronin made his debut for Munster in 2012 and the last of the Corkman's three Test appearances to date came against France in the 2016 Six Nations.
Prednisolone and prednisone are glucocorticoids, commonly used anti-inflammatory steroids, which have been abused in some high-performance sports as they boost red blood cell production and aid speedier return to action following injury.
The decision of the independent Judicial Officer is final in respect of the player and EPCR, however World Rugby, Sport Ireland and WADA each has the right to appeal.
Flanagan said: "This has been an extremely challenging time for James and the province, and we are glad it has reached its conclusion. We have treated this matter with the utmost seriousness, and as always Munster Rugby and Irish Rugby are fully supportive of all Sporting Ireland, WADA and World Rugby anti-doping policies.
"In protecting the integrity of our player, the organisation, and the sport, I can assure you that this unintentional anti-doping rule violation is as a result of exceptional circumstances due to a third-party dispensing error by a pharmacy," he added.
"Clearly the sanction is reflective of the strong mitigating factors in this case, and we look forward to James' return to action."