Santillan (back/hamstring) was activated from the 60-day injured list Thursday, Charlie Goldsmith of The Cincinnati Enquirer reports.
Finally recovered from lingering back and hamstring injuries, Santillan will be available out of the Reds' bullpen -- for the first time this season -- Thursday afternoon against the Nationals. The 26-year-old right-hander holds a career 3.71 ERA with 77 strikeouts in 63 major-league innings.