This is a question that will vary amongst various plastic surgeons. After a breast reduction procedure, the vasculature to the nipple-areolar complex (NAC) specifically, but also to the entire breast/incisions is often times very tenuous. Ice may provide some comfort and decrease swelling, however, the cool temperature cause vasoconstriction of these blood vessels can cause issues with getting enough blood flow to all of these areas. I would discuss this with your plastic surgeon and follow his/her recommendations. In the immediate postoperative period following this procedure, I typically avoid ice/cool packs to the breast itself for fear of the aforementioned issues with vascularity to the NAC. I recommend pain medications, compression bras, and sometimes warm pads for comfort. Hope that this helps! Thank you for the question and best wishes for a terrific result!