It was his second time on that list this season. The first came on April 14 shortly after his 2-year-old son was hospitalized with rattlesnake bites. He was placed back on the list on Tuesday but the team said it was not related to his son, who they said is doing fine.
Axford is 1-1 with 13 saves and an ERA of 2.42 in 24 appearances this season.
To make room, the Rockies optioned right-hander Justin Miller to Triple-A Albuquerque.