The 66-year-old rocker's press service said Thursday the situation is "under control."
Hallyday, an entertainment icon for decades, underwent surgery in Paris on Nov. 26 for a herniated disc, then traveled to Los Angeles.
His press service said lesions from the initial operation "required reparative surgery." He had also suffered an infection following the first operation.
Hallyday is on a multi-city tour called "Route 66," a reference to his age and an homage to American rock that has inspired his music. The tour is billed as his last.