Hot cold packs are helpful and important tools in most medical for home care therapies. To use them properly, find out if your condition requires heat or cold therapy. Heat therapy should be used to relax muscles and stimulate blood circulation, cold therapy to numb sharp pain and aid in the reduction of swelling. Always cover the pack with cloth before applying it on the skin and do not leave it on the skin for longer than 15 to 20 minutes to prevent burns and frostbite. Adhering to these simple measures can greatly improve your healing and recovery time as well as your general health.