The decision is retroactive to Aug. 15.
Scherzer, 12-5 with a 2.25 ERA and 220 strikeouts this season, left a start and then sat out a game with neck spasms earlier this month. Nationals manager Dusty Baker said Friday's soreness was on the other side of the right-hander's neck.
"We're just taking the cautious route, and then hopefully we'll find out what's causing this to move from one side to the other side," Baker said before Friday night's game against the San Diego Padres. "That's the word right now, and hopefully he'll be out there to make his next start."
Baker said Scherzer's early arrival to the clubhouse Friday tipped him off that something was off.
"I knew something's wrong, cause usually he's not here as early as he was here," Baker said. "On the days he's pitching, he normally shows up a little bit later. But he was here when I got here. That showed me that either he's changed his program, or something's gone wrong."
The right-hander, who is eligble to return Aug. 25, was replaced on the mound by left-handed reliever Matt Grace. The third-year veteran was making his first career start.
Scherzer's DL stint comes just as Washington is set to have Stephen Strasburg return the mound on Saturday. It will be Strasburg's first start in four weeks after battling a nerve injury in his elbow.