Ryu was diagnosed with his latest injury 12 days after returning from elbow surgery. He had been out for nearly two years when he took the mound almost two weeks ago against the San Diego Padres.
Ryu went on the DL on Tuesday along with right-handed reliever Casey Fien, who also has elbow tendinitis.
Joc Pederson (sprained shoulder joint) was activated from the disabled list before Tuesday's game at the Washington Nationals, as expected. He was in the starting lineup, playing center field and batting sixth. Also added to the roster was left-handed reliever Luis Avilan.
Ryu, who had Tommy John surgery in 2004 when he was in high school in South Korea, is not believed to be seriously injured. He reportedly had an MRI in recent days that did not show anything significant.
Ryu's comeback this year had been halted on multiple occasions, the first time in spring training. His minor league rehab assignment was also put on pause for a short while. His velocity had been down throughout his rehab, but the Dodgers had downplayed it.
He was supposed to make his first start of the second half on Wednesday against the Nationals. The Dodgers have not announced who will replace him on the mound.
The club has multiple starting options in the minor leagues such as Ross Stripling, Brock Stewart and Julio Urias, all of whom have made their major league debut at some point this season. Urias seems less likely because the Dodgers are keen on keeping the left-hander's innings totals low this season.