The reliever, who spent much of last year on the DL with shoulder tendinitis, last pitched Saturday in a walk-off loss to the Cubs. He hit a batter, and surrendered a double and single, allowing the game-winning run to score.
Reds manager Bryan Price confirmed Cingrani has inflammation in his shoulder, but that "it doesn't sound like" the lefty has any structural damage. After the reliever struggled against Chicago, he was sent for further evaluation to Cincinnati, where an MRI revealed the extent of the injury.
"That's what I know right know," Price said.
Cingrani has been a valuable member of the bullpen, compiling a 3.47 ERA in 24 appearances. The lefty hadn't been as effective this month, though, and allowed a run as part of Cincinnati's 9-7 loss to San Diego on June 6.
Price didn't put a timetable on Cingrani's return.
"I do imagine it's going to take some time to get the inflammation out, get the strength back up in the shoulder and then reinitiate throwing," Price said. "He's got 15 days, and we'll see where he is at that point."
In a corresponding move, the Reds recalled Pedro Villarreal from Triple-A Louisville. The 27-year-old righty has surrendered four runs over 4 2/3 innings for Cincinnati this year. He has a 3.81 ERA in 19 relief outings for Louisville.
Alejandro Zúñiga is an associate reporter for MLB.com. Follow him on Twitter @ByAZuniga.