Tell patients to choose direct moist heat rather than dry heat when attempting to ease muscle tension or spasm. Direct moist heat is less drying to the skin, less apt to cause burns, less likely to cause excessive fluid and salt loss through sweating, and more likely to penetrate deeper tissues. Instruct the patient to apply heat for 20 to 30 minutes, as follows:

• Place a moist towel over the painful area.
• Cover the towel with a hot-water bottle properly filled and at the correct temperature.
• Remove the hot-water bottle and towel after 20 to 30 minutes. Don’t continue the application for longer than 30 minutes, because therapeutic value decreases after that time.