Heat is very effective at treating chronic neck and back pain. Ice is often used for more recent injuries (after surgery, pulled muscles, etc.) Heat brings blood flow into muscles and can help with muscle stiffness and spasms. A heating pad set at low to medium (never high) can be effective. Use heat as needed for 15 minutes every 2 hours. NEVER fall asleep while using a heating pad. If used too long or at too high of a temperature, heating pads can cause severe burns. Do not heat fresh injuries; this can cause increased swelling and inflammation. Following a fresh injury, it is often recommended to use ice. After a few days when the pain starts to subside it is often best to switch to heat. If you find that heat is not working, switch to ice. Ultimately, your personal preference is most important.