The 31-year-old, who served a seven-month worldwide ban for using cocaine while at Stamford Bridge, tested positive after playing for Fiorentina earlier this month.
Mutu could be banned for four years if the findings of the Italian Olympic Committee are upheld.
“He is a little worried but we are optimistic,” said Mutu’s agent Victor Becali. “He will probably ask for analysis of the B sample.”
The Romania international is still dealing with the fallout from his cocaine scandal, more than five years after his sacking by Chelsea for gross misconduct. Mutu is awaiting an imminent verdict in a long-running legal battle over whether he owes the Blues £14.5m for breach of contract. He has already lost two appeals against the fine, which would compensate Chelsea for the loss of a player who cost them £15.8m in 2003.
The forward, who made his name at Parma before becoming one of the first signings of the Roman Abramovich era, has rebuilt his career in Italy. Mutu has shone this season, scoring seven goals and being linked with a move back to the Premier League, with Manchester City.
Sibutramine, a stimulant used to treat obesity, has been banned in Britain over links with heart attacks and strokes.