Manager Dave Roberts had implied some sort of move could be made after Syndergaard allowed six runs and seven hits in three innings Wednesday as the Dodgers' losing streak hit four with an 8-6 loss to the Cincinnati Reds.
"Noah has been going through it all year. It is not from lack of effort or preparation. It's just not working," Roberts said after the loss. "There's things with that blister. There was a fingernail break tonight. He's not going to make excuses. He understands about performance."
On Thursday, Roberts said they expected Syndergaard to be out at least a few weeks to "reset" physically, mentally and emotionally.
"The physical, the mental, the emotional part, as he's talked about, has taken a toll on him," Roberts said Thursday. "So, the ability to get him away from this. He left today to go back to Los Angeles to kind of get back to normalcy."
Robers added: "I think searching and not being comfortable with where he was at in the moment is certainly evident in performance. So hopefully this time away will provide more clarity on who he is right now as a pitcher.
"Trying to perform when you're searching at this level is extremely difficult. I applaud him from not running from it, but it's still very difficult. Hopefully it can be a tale of two stories, two halves when he does come back."
Syndergaard, who signed a one-year, $13 million deal with the Dodgers during the offseason, saw his ERA balloon to 7.16. He has given up five runs or more in three straight starts and six earned runs or more in four starts this season overall, tied with Cincinnati's Graham Ashcraft and the Oakland Athletics' Kyle Muller for the most in the majors.
He previously had expressed displeasure with his performance, calling himself the rotation's "weakest link" last week.
Syndergaard, 30, missed all of 2020 after undergoing Tommy John surgery and has a 4.71 ERA over the past two-plus seasons. The right-hander went 10-10 with a 3.94 ERA last season with the Angels and National League-champion Phillies.
The Dodgers recalled right-hander Tayler Scott from Triple-A Oklahoma City in a corresponding move. Scott, 31, allowed zero runs and one hit over the final two innings of Thursday's 6-0 win over the Reds to end the losing streak.
The Associated Press contributed to this report.