Carrera began his pro career in 2001 and captured the WBA middleweight title by knocking out Javier Castillejo in 2006. Carrera tested positive for an illegal substance following the win over Castillejo, and the bout's result was officially overturned to a no-contest. His urine test was confirmed to have tested positive for the steroid Clenbuterol.
Carrera's professional career began in 2001 and he won the WBA middleweight title by defeating Javier Castillejo with a knockout in 2006. However, his victory was later complicated when he tested positive for a banned substance, leading to the result being changed to a no-contest. The test revealed Clenbuterol, a steroid that is prohibited in professional sports.