"Yordan has been suffering with the injury for a couple weeks and it's gotten worse," Astros manager Dusty Baker told reporters, according to the Houston Chronicle. "We decided that hey, the only way to get this well is to try to use these (series) before the All-Star break to coincide with the 10 that he has to be on the IL."
The injury, which Alvarez suffered on a swing during a game on June 18, was "bothering him every swing," Baker told reporters.
The outfielder and designated hitter will miss the Astros' next two series before the All-Star break and likely won't be able to play in the All-Star Game.
He leads the Astros in hits (82), batting average (.306), home runs (26), RBIs (60), on-base percentage (.405), slugging percentage (.653) and OPS (1.058).
Outfielder Jose Siri was recalled from Triple-A Sugar Land in a corresponding move.
The Astros currently hold the second-biggest division lead in the major leagues with a 12-game lead in the American League West over the Seattle Mariners.