They both have their place in treating and inflammation. Ice or other cold treatments are usually used in the early stages of an injury. Cold applied to the injured area makes the blood vessels get narrower (vasoconstrict), limiting the swelling of the initial period of healing. Cold treatments should be applied for about 15 minutes, three to four times a day for the first two or three days after the injury.
In some cases, heat is helpful two or three days after the injury. Heat makes the blood vessels get larger (vasodilate). This brings more blood to the area, infusing it with nutrients and oxygen to help healing and flushing away chemicals that have built up in the injured tissue. True heat, such as moist hot packs, heating pads, or warm showers or baths, are better than creams that just make the skin feel hot. Heat treatments should usually be held on the injured area for 15 to 20 minutes, three to four times a day. Be careful not to burn yourself by routinely checking your skin for extra redness.