Pissilli tested positive for the diuretic Finasteride at the Omnium National Championship on June 29, the Italian Olympic Committee said Wednesday.
Pissilli, who plays on the Italian pro tour, was suspended by the Italian Golf Federation. He could face a two-year ban if found guilty of a doping violation.
His local golf club in Florence released a statement later Wednesday, saying he had informed authorities at the time of the test that he had taken the drug for almost two years to treat a prostate problem.
Golf has come under increased pressure from the World Anti-Doping Agency to introduce random drug testing after South African veteran Gary Player claimed at the British Open that some golfers were taking performance-enhancing drugs.
Finasteride also is used to treat hair loss but can mask steroid use. It has been at the center of several recent doping cases.
American skeleton slider Zach Lund missed the 2006 Turin Olympics because of a one-year doping suspension triggered by his use of the drug. He was later cleared of wrongdoing by the Court of Arbitration for Sport.
French runner Nordine Gezzar and former Premier League soccer player Stan Lazaridis of Australia also have tested positive for Finasteride.
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