When an acute injury occurs, athletic trainers have a certain procedure that is followed, in order to minimize the extent and severity of the injury. Cold compress or ice is applied immediately to inhibit swelling of the inflamed tissue. After the swelling has been controlled, heat is applied to increase healing and circulation to the damaged tissue. Heat and cold are then alternated for 12 hours.
When using a modality, such as a cold or ice wrap, the suggested time is about 20 minutes. This is only a guideline and depends on individual tolerance. When using heat, moist heat is usually preferred, making the heat more effective and soothing. When using either modality of heat or cold, insulation from the skin is mandatory. The skin should be protected with a towel or any material that has insulating properties; cotton is best. If discomfort persists, seek medical attention.
(Source: Under Pressure: Fast and easy relief from the pressures of modern life with the ancient science of pressure point therapy. By John Sherman, M.D., OTR, CST.)