Many people are confused as to the correct application of ice packs or heat packs to treat an injury or the often uncomfortable symptoms associated with a range of other conditions. While there is a distinct time for cryotherapy (ice) and one for thermotherapy (heat), knowing when to use each one can make a big difference in the healing process.
Since cold therapy causes vasoconstriction to slow down blood circulation to a specific area, it is the therapy of choice within the first 72 hours. Cold compresses will reduce the pain, inflammation, and stiffness after an injury. Cold decreases the flow of fluid (lymph) to tissues and slows the chemicals that cause pain. Also, cold decreases the nerve ending conduction of pain messages and reduces muscle spasms. However, cold therapy should be avoided if you have circulation issues or sensitivity to cold. The best way to apply a cold compress is to place a towel between your skin and the cold pack. Use it for 10 minutes at a time while elevating the affected area.
Heat therapy encourages blood vessels to expand and brings more blood to the area. So you want to apply heat after the initial 72 hours after an injury. Since it lowers the transmission of pain signals, heat can be relaxing and sedating. With increased blood flow comes more oxygen and nutrient flow to heal the damaged tissues. The application of heat also encourages greater flexibility and reduces stiffness.
A combination of hot and cold therapy often provides an excellent method of care as heat sedates muscles and joints and cold drives out swelling.