Tigers manager AJ Hinch said Skubal will visit with a specialist next week to address his arm issue, with specific focus on his elbow.
"We're concerned about Tarik," Hinch told reporters. "He's not going to pitch for the rest of the season. That much we know. ... The inflammation, the pain he'd felt, it continued when he started throwing again."
Skubal, 25, last pitched Aug. 1. He was pulled from that game after complaining of left arm fatigue and underwent testing to determine the severity. Skubal was placed on the 60-day injured list before Friday's 2-0 loss to the Chicago White Sox.
In 21 starts this season, Skubal is 7-8 with a 3.52 ERA.
Skubal was replaced on the roster by left-hander Daniel Norris. Norris, who was making his first appearance with the Tigers after signing a minor league contract late last month, allowed four hits and struck out one with two walks in 4⅔ innings.
The Associated Press contributed to this report.