Alfonzo was penalized Wednesday by the commissioner's office for a second violation. He was suspended for 50 games in April 2008 while a member of the San Francisco Giants.
Alfonzo said then he never knowingly took steroids but did take medicine for bronchitis while home in Venezuela. He said he was surprised by the latest positive test and intends to fight the penalty in arbitration.
Manny Ramirez retired in April rather than face a 100-game suspension following a second positive test.
A third violation would carry a lifetime ban.