Heat and ice have been used for many years to treat pain and to reduce swelling, and many people have found them effective. More recently, studies have been done to investigate whether heat and ice really make a difference to healing and the results have been inconclusive. In general, when used sensibly, they are safe treatments which make people feel better and have some effect on pain levels but there are also few harms associated with their use.
Heat is an effective and safe treatment for most aches and pains. Heat can be applied in the form of a heat bag, heat pads, deep heat cream, hot water bottle or heat lamp.
Heat causes the blood vessels to open wide (dilate). This brings more blood into the area to stimulate healing of damaged tissues. It has a direct soothing effect and helps to relieve pain and spasm. It can also ease stiffness by making the tissues more supple.
If heat is applied to the skin it should not be too hot; gentle warmth will be enough. If excessive heat is applied there is a risk of burns and scalds. A towel can be placed between the heat source and the skin for protection and the skin must be checked at regular intervals.
Heat should not be used on a new injury. It will increase bleeding under the skin around the injured area and may make the problem worse. The exception to this is new-onset low back strains. A lot of the pain in this case is caused by muscle spasm rather than tissue damage, so heat is often helpful. A large-scale study suggested that heat treatment had a small helpful effect on how long pain and other symptoms go on for in short-term back pain. This effect was greater when heat treatment was combined with exercise.
Heat is often helpful for different types of pain including aching muscles from over-exertion, aching pains from fibromyalgia and other chronic pain condition, and cramping or spasm pains such as menstrual pains.
Ice has traditionally been used to treat soft tissue injuries where there is swelling. However, there is a growing body of evidence which suggests that applying ice packs to most injuries does not contribute to recovery and may even prolong recovery. This is related to the fact that reducing the temperature at the site of an injury will delay the body’s immune system response. It is the action of the immune system which will heal the injury.
In one study, some people who used ice said that it was helpful for managing pain, although this did not translate into a lower use of painkillers. Many people find that ice is helpful when used to manage pain in the short term. It is unlikely that it will have much of a negative effect in the long term when used in this way.
Ice can also be helpful to reduce swelling of surgical wounds. With any sprain, strain or bruise there is some bleeding into the underlying tissues. This causes swelling and pain. Ice treatment may be used in both the immediate treatment of soft tissue injuries and in later rehabilitation.
During immediate treatment, the aim is to limit the body’s response to injury. Ice will reduce bleeding into the tissues, prevent or reduce swelling (inflammation), reduce muscle pain and spasm by numbing the area and by limiting the effects of swelling. These effects all help to prevent the area from becoming stiff, by reducing excess tissue fluid that gathers as a result of injury and inflammation.
In the later, or rehabilitation, phase of recovery the aim changes to restoring normal function. At this stage the effects of ice can enhance other treatments, such as exercise, by reducing pain and muscle spasm. This then allows better movement. If you are doing exercises as part of your treatment, it can be useful to apply an ice pack before exercise. This is so that after the ice pack is removed the area will still be a little numb. The exercises can also be done with the ice pack in place. This reduces pain and makes movement around the injury more comfortable, although it can also make the muscles being exercised stiffer.
Precautions when using heat and ice
Do not use heat or cold packs:
- Over areas of skin that are in poor condition.
- Over areas of skin with poor sensation to heat or cold.
- Over areas of the body with known poor circulation.
- If you have diabetes.
- In the presence of infection.
- Also, do not use ice packs on the left shoulder if you have a heart condition. Do not use ice packs around the front or side of the neck.
Ice causes a longer-lasting effect on the circulation than heat and the painkilling properties of ice are deeper and longer-lasting than heat.
Both heat and ice can be re-applied after an hour if needed.