Cincinnati Reds left-handed starter Brandon Wiliamson, who missed the 2025 season following Tommy John surgery, went on the 15-day injured list on Thursday with left shoulder fatigue.

In a corresponding move, the Reds recalled right-handed reliever Zach Maxwell from Triple-A Louisville.

Williamson, 28, last pitched on Wednesday night, allowing four runs on four hits with four walks and four strikeouts before he exited after three innings of a 13-2 home loss to the Colorado Rockies.

He had an MRI exam on Thursday morning.

“Structurally, it came back good, so that’s good,” manager Terry Francona said. “Dr. (Tim) Kremchek looked at him, injected his shoulder with cortisone and he will go on a shoulder program — range of motion, strength and all that stuff.”

Williamson is 2-3 with a 6.11 ERA, 19 strikeouts and National League-high 20 walks in 28 innings over six starts this season.

For his career, Williamson is 7-8 with a 4.69 ERA, 64 walks and 129 strikeouts in 159 1/3 innings over 33 games (32 starts) for the Reds in 2022-24 and 2026.

Williamson spent five months on the injured list following a left shoulder strain in 2024, then four games into his return, he tore the ulnar collateral ligament in his left elbow and sat out the 2025 campaign.

Maxwell, 25, is the No. 17 prospect in the Reds organization per MLB Pipeline. He pitched 10 innings as a rookie in 2025 and had a 4.50 ERA with four walks and 13 strikeouts in eight relief appearances.

This season, the 6-foot-6, 275-pound Maxwell is 1-0 with a 5.91 ERA in 12 appearances at Louisville.

Cincinnati selected Maxwell in the sixth round of the 2022 MLB Draft out of Georgia Tech.

–Field Level Media