The Reds activated Lowder (shoulder) from the 15-day injured list Sunday.
Lowder landed on the injured list May 13 due to right shoulder discomfort, and he's slated to make his return as Sunday's starting pitcher after missing just over three weeks. The right-hander tossed 70 pitches for Triple-A Louisville on Tuesday in his lone rehab appearance, so he may be held to a pitch count in his return to the big-league rotation. To make room for Lowder on the 26-man roster, Cincinnati optioned reliever Luis Mey to Louisville.