The Giants placed Hicks on the 15-day injured list Tuesday with right shoulder inflammation, retroactive to Aug. 25.
Hicks surrendered one earned run over two-thirds of an inning during his latest appearance Saturday, though he appears to have come away from the outing with an injury. He'll now be sidelined until at least mid-September, and the Giants will recall Austin Warren from Triple-A Sacramento to replenish their bullpen depth.