The 26-year-old right-hander left Saturday's game against the San Francisco Giants in the fourth inning after experiencing tightness in his left side.
Strasburg allowed one hit over 3 2/3 scoreless innings in his third start since coming off the disabled list. He missed nearly four weeks due to neck tightness.
Though only 5-5 with a 5.16 ERA in 2015, in his previous two starts since returning from his earlier DL stint, Strasburg went 2-0 with a 1.50 ERA and 15 strikeouts. He dominated the Giants before leaving.
The Nats called up right-hander Taylor Jordan from Triple-A Syracuse to replace Strasburg on the roster.
Information from The Associated Press was used in this report.