Strasburg was placed on the IL five weeks ago with right shoulder inflammation.
In Strasburg's last start, a loss to the St. Louis Cardinals on April 13, he was tagged for seven earned runs on eight hits and gave up five walks in four-plus innings.
Strasburg's average velocity in the game was 90.6 mph, a little more than 2 mph slower than in his season debut. He was placed on the IL a few days later.
Strasburg, 32, is 0-1 with a 6.30 ERA in two starts this season. The Nationals are last in the tightly contested NL East with a 17-23 record.
The Associated Press contributed to this report.