Brazil midfielder Fred tested positive for banned substance hydrochlorothiazide, the country's football confederation has confirmed.
The Brazilian Football Confederation (CBF) said it would support the 22-year-old Shakhtar Donetsk man.
Hydrochlorothiazide is a diuretic that can be used as a masking agent.
The CBF said in a statement on Friday it had provided a list of medications and their usages to organisers two months before the start of the Copa America.
Hydrochlorothiazide was not part of the list, nor was it available to the CBF, the confederation said.
Fred started two games for Brazil as they reached the quarter-finals in Chile before being knocked out by Paraguay.
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