Shakhtar Donetsk and Brazil international midfielder Fred has been handed a one-year ban for doping, South American football's governing body CONMEBOL said.
The 22-year-old tested positive to the diuretic hydrochlorothiazide in June during the Copa America in Chile, reports Xinhua.
Normally used to control hypertension and cardiovascular problems, hydrochlorothiazide is also a known masking agent for performance-enhancing drugs.
Monday's announcement followed a month-long hearing into the case by Conmebol's disciplinary committee in Asuncion.
The ban, backdated to July 26, is valid for all CONMEBOL-sanctioned matches, meaning he is still eligible to play for Shakhtar. However world football's governing body FIFA could decide to apply the penalty across all competitions.
Fred, who has repeatedly protested his innocence, is expected to appeal the decision.