The Portuguese midfielder tested positive for banned substance Furosemide following Fluminense's match against Boavista on March 30 in the Campeonato Carioca
The Portuguese midfielder, who plays for Brazilian champions Fluminense, tested positive for banned substance Furosemide following his side's clash with Boavista on March 30.
The 35-year-old has not travelled with the squad for their Copa Libertadores clash with Emelec in Ecuador this Thursday.
Deco is believed to have ingested the substance through some vitamin supplements, which he purchased at a pharmacy. Reports in Brazil claim he has appointed solicitors to take action against the company that produce the product he bought.
The news comes just two weeks after another doping case hit Brazilian football, when Vasco da Gama midfielder Carlos Alberto tested positive for two banned substances following a 3-2 win over Deco's Fluminense side in early March.
Earlier on Tuesday, Eufemiano Fuentes was found guilty of endangering public health by a court in Spain after a lengthy investigation into suspected doping offences in both cycling and European football.
Deco represented Chelsea between 2008 and 2010, scoring six goals in 57 appearances.