Heating pads are one kind of pain reliever, which are used in hospital and can also be used personally in house. These pads are required to be heated by, and then used to manage pain by warming of the targeted part of the body. The pads are effective as they cause the blood vessels of the affected area to get dilated, which further enhances perfusion to the targeted tissue. There are basically three types of heating pads: electrical, chemical and hot water bottles. An electric heating pad can be heated using household current and must have protection against overheating. Physical therapists usually use moist heating pads, which are not ideal for home use. Chemical heating pads use chemical like sodium acetate. These pads employ a one-time exothermic chemical reaction such as catalyzed rusting of iron. The reagents are stored in separate compartments within the pad. The heat is produced, when squeezing of the pad break the reagents and mixes those together.