Hot packs and cold packs are useful and comforting for a number of conditions. These therapies are non-invasive, non-addictive and generally safe if you follow some basic guidelines.
What Hot Packs Do
Hot packs increase blood flow, which brings oxygen and nutrients to an area and speeds the removal of waste products. Heat can also relax tense muscles and relieve pain.
What Cold Packs Do
Cold packs slow down the blood flow. This can slow down inflammation, prevent muscle spasms and reduce pain.
Always wrap hot or cold packs in a towel or some other cloth. Direct heat can burn the skin, and direct cold can cause nerve damage.
Punctured or broken packs (hot or cold) should be discarded immediately. The substances in these packs can damage your skin. Old packs should be discarded because they may damage easily.
Standard procedure for sports injuries is to apply cold right after the injury, then switch to heat after the pain subsides. Heat is best for old or chronic pains. Cold is best for throbbing or inflamed situations.
The first heat packs were hot water bottles. Electric heating pads are more convenient. There are gel-filled items that retain heat after being microwaved. The original cold pack was crushed ice wrapped in a towel--this is still common in the sports world. There are gel-filled packets that retain cold after being placed in the freezer--these are often cheaper and easier to find if you buy the ones disigned for food coolers. The latest innovation is the hot-cold pack. It can be used as a heat pack (they go in the microwave) or a cold pack (they go in the freezer).