Hot and Cold Packs


When is it best to apply cold and when to apply heat? At first it may seem like a simple question. Surely they’re opposite and one is right and one is wrong. Not so! Confusion occurs because, although there are a few fundamental rules, there are other factors which influence which modality is best applied under certain circumstances. You’ll find some difference of opinion among physios and doctors too, but for what it’s worth here’s my advice.


Why do Either?

The human body adapts to changes in temperature to ensure survival. This is done by regulation of blood flow (circulation) by dilation or constriction of the smooth muscle walls of the arteries. When applying heat or cold therapy, we are simply taking advantage of the natural reactions of the body to help with the healing of a local injury.

Cold Therapy

There are several reasons we use cold therapy:

– Applying a cold pack for 15-20 minutes will cause a constriction of the blood vessels reducing circulation to the area. This is particularly desirable immediately after an injury when internal bleeding and swelling occur.

– Removal of excess fluid through the lymphatic system is increased for 25 minutes after application of a cold pack.

– It provides a ‘numbing’ pain relief which is particularly effective on sharp or acute pain.

– It can either increase or decrease muscle tone or spasms depending on how long it’s applied.

Remember ice burns can occur if applied for too long, especially over bony prominences where there is only a thin layer of skin over the top (e.g. the ankle). You can repeat the application safely every two hours, although many people can tolerate re-application after an hour off.


The most common method of applying cold therapy is with a cold pack. Blue gel packs are conveniently re-useable, mouldable and cost-efficient. Frozen peas are commonly used also. Wrapping the pack in a wet cloth or towel dramatically increases the effectiveness of this method. If you don’t tolerate the pack being that cold initially, try applying it with a thin dry cloth for five minutes then wet the cloth.

To combine the benefits of massage and cold therapy try using the ice massage technique. Using a double width of styrofoam cups, fill them near to the top with water and freeze them. Then cut or tear off a strip around the top of the cups, exposing the ice stick within. Hold the bottom of the foam cup and rub the affected area with the ice. You must keep it moving and continuously dry the area to prevent getting an ice burn. Do this for 15-20 minutes.

Heat Therapy

The reasons for applying heat therapy are:

– Applying heat to an area for 15-20 minutes will cause dilation of blood vessels and increased local circulation. This is essential for tissue healing because it brings oxygen and nutrients for cell repair.

– It provides ‘soothing’ pain relief which is particularly effective on arthritic or chronic pains.

– It causes relaxation of muscle spasm

– It allows soft tissues to be stretched or deformed more easily.

Most people should be aware of the danger of burns from heat applications and take appropriate measures to protect their skin.

Heat wheat packs are mouldable and provide a sustained comfortable warmth. Check the instructions on how long to microwave the pack for then test for yourself – the appropriate time will depend on the power of your microwave. Also be aware that the temperature keeps increasing for the first three to five minutes after removal from the microwave. Blue gel packs heated in boiling water are also convenient and mouldable but don’t last as long.

A hot water bottle is best on flat areas such as the back. Electric heat pads are popular with chronic pain and arthritis patients who use heat therapy daily. They are quite safe, cover a large area, are mouldable and can be set at a constant temperature.

Direct warm water application such as a bath or shower has benefits in relaxing muscle spasm and providing pain relief. No doubt the pleasant sensory effect of water hitting the skin in the shower or turbulence in a spa bath contributes to the effectiveness.

The Ground Rules

1. Acute injuries (i.e. a new injury) with pain, swelling, internal bleeding and muscle spasm must be treated with cold therapy for the first 48-72 hours. Never apply sustained heat therapy. Only a brief warm shower may be appropriate for acute spinal pains as it seems to help with relaxing muscle spasm. Examples of acute injuries include spraining your ankle, injuring your back lifting or waking up with a sharp pain and spasm in your neck.

2. Chronic arthritic pains prefer heat therapy. Examples include arthritic spinal pain and osteoarthritic knees. Be aware that if you suffer a flare-up of an existing condition that it may be best treated as an acute injury.

3. Subacute conditions (3-5 days post injury) will benefit from both heat and cold therapy. Heat will provide oxygen and nutrients for cell repair while cold will settle any inflammation, drain swelling, provide pain relief and relax muscle spasm. You can apply heat and cold therapy separately (with a short break in between) or together, in a contrast bathing application. Using any methods of heat and cold therapy mentioned previously, alternate application every 1-2 minutes for 20 minutes. Examples include five day old quads muscle strains, ankle sprains or spinal pain.

4. Chronic inflammatory conditions respond best to contrast bathing technique. Examples include ongoing patella tendon, achilles and shoulder tendonitis, shin splints, plantar fascitis and ITB pain.

5. Temperature, culture and climate affect the tolerance and effectiveness of each modality. In hot, humid climates cold therapy is usually preferred while in colder countries heat therapy has historically been favoured.

6. When in doubt use cold therapy. It will rarely exacerbate a condition (as heat can) and will help most problems. Clinically we see many patients who report improvement the day after using cold packs even though heat packs feel better at the time of application.

The Take Home Message

Correctly using heat and cold therapy will provide great benefit in speeding your recovery from injury. They are easy, inexpensive and can be accessed almost anywhere, anytime.


Posted by | View Post | View Group