The Royals placed Gonsolin on the 15-day injured list Sunday due to an allergic reaction.
James McArthur (elbow) was reinstated to take Gonsolin's spot on the active roster for the final day of the regular season. Gonsolin spent most of the year on the mend from Tommy John surgery with an internal brace, returning for a lone big-league appearance Sept. 22, when he allowed five runs on four hits and three walks while striking out five over 2.2 innings against the White Sox.