This leaflet gives a general overview of ice and heat in the treatment of soft tissue injuries. If you are uncertain about the use of ice or heat, consult a health professional such as a doctor, nurse or physiotherapist.
With any sprain, strain or bruise there is some bleeding into the underlying tissues. This may cause swelling and pain and can delay healing. 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.
- Reduce pain 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.
How do you make ice packs?
Ice packs can be made from ice cubes in a plastic bag or wet tea towel. A packet of frozen peas is also ideal. These mould nicely and can go in and out of the freezer. However, frozen vegetables should not be eaten if they have been thawed and re-frozen. Purpose-made cold packs can also be bought from pharmacies. Take care when using ice and cold packs from a deep freeze, as they can cause ice burns quickly if used without care and proper protection.
How are ice packs used?
- Ideally, rub a small amount of oil over the area where the ice pack is to go (any oil can be used, even cooking oil!). If the skin is broken or there are stitches in place, do not cover in oil but protect the area with a plastic bag. This will stop the wound getting wet.
- Place a cold wet flannel over the oil (you do not need to if using a plastic bag).
- Place the ice pack over the flannel.
- Check the colour of the skin after 5 minutes. If it is bright pink or red remove the pack. If it is not pink, replace the bag for a further 5-10 minutes.
- Ice can be left on for 20 to 30 minutes but there is little benefit to be gained by leaving it on for longer. You run the risk of damaging the skin if ice is left on the skin for more than 20 to 30 minutes at a time.
- The effect of the ice pack is thought to be improved if it is pressed gently on to the injured area.
Note: ice can burn or cause frostbite if the skin is not protected with oil and/or other protection such as a wet flannel.
How long should ice be applied for?
Ideally, ice should be applied within 5-10 minutes of injury for 20 to 30 minutes. This can be repeated every 2 to 3 hours or so whilst you are awake for the next 24 to 48 hours.
After the first 48 hours, when bleeding should have stopped, the aim of treatment changes from restricting bleeding and swelling to getting the tissues remobilised with exercise and stretching. Ice helps with pain relief and relaxation of muscle tissue.
When an injury is older than 48 hours, heat can be applied in the form of a wheat bag, heat pads, deep heat cream, hot water bottles or heat lamps. 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 hot; gentle warmth will suffice. If excessive heat is applied there is the risk of burns and scalds. A towel can be placed between the heat source and the skin for protection. The skin must be checked at regular intervals.
Do not use heat on a new injury. This will increase bleeding 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 more helpful than ice.
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.
Precautions when using heat and ice
Do not use cold packs or heat:
- 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.
Dr Tim Kenny
Dr Jan Sambrook
Dr Helen Huins