Although it seems like a simple concept, one question that we are commonly asked is when to use ice versus heat therapy to treat pain.  In this post, we will discuss how each one works on a physiologic level, and when to use each one.  Both heat and cold therapy are an inexpensive and easy-to-use treatment for the management of acute, chronic, and postoperative pain.  These therapies are also great to use after vigorous exercise to stimulate healing.  One main point to keep in mind is that ice reduces inflammation, while heat stimulates blood flow.  Knowing that simple fact can help if there’s ever a question about when to use which one.

Cold Therapy

Cold therapy such as ice baths or ice packs are commonly used for the treatment of acute, injury provoked pain.  As previously mentioned, cold therapy reduces inflammation.  When the body is undergoing an inflammatory response, many chemicals are secreted and directed to the injured area.  These chemicals are used to stimulate healing.  While the end result is the body repairing itself, inflammatory responses can be somewhat painful.  Due to the abundance of chemicals released, other symptoms such as redness, swelling, and pain are often experienced as well.  Cold is a great option because it not only reduces inflammatory symptoms, it can be an analgesic as well.  Topical application of cold or ice will decrease the temperature of the skin, muscles, and even inside our joint capsules.  Cold also slows the conduction velocity of peripheral nerves, which can mask or override our sensation of pain.  One way that cold can actually treat pain instead of just numbing or masking it is by its effect on swelling and edema.  Cold causes vasoconstriction, which slows the bloodflow to the area, reducing the amount of fluid buildup and the symptoms that go along with that.

Heat Therapy

Unlike cold therapy, heat therapy stimulates blood flow.  This is helpful in the treatment of pain due to chronic, overuse type injuries or disease processes.  Pain from sore or tight muscles is often associated with a buildup of lactic acid.  Applying heat to these areas helps to stimulate the flow of oxygen-rich blood which can decrease the amount of lactic acid in the muscles, thereby decreasing pain and improving range of motion.  Heat may also lead to pain relief by way of muscle relaxation. When using heat at therapeutic levels, collagen tissue relaxes and elongates, easing tension built up in the muscles.  Using heat in conjunction with a stretching or home exercise program or along with a formal physical therapy program will provide the greatest results.

Similarities between Heat and Cold Therapy

Something that heat and ice both have in common is that they both reduce muscle spasms and alleviate pain. Both applications also have an effect on free nerve endings within our tissues.  The effects that both heat and ice have on the peripheral nerves may increase the pain threshold among patients.

 When to Use What?

Using ice is critical for use after procedures such as total joint replacements, joint manipulations under anesthesia, fusions, tendon repair, etc. For example, after a total knee replacement, there is bleeding into the joint that occurs post operatively.  Because of the joint capsule, this bleeding stays contained in the joint, and isn’t actively visible.  Using ice to slow some of this bleeding is so important for a few reasons.  Bleeding into a joint post operatively can cause a hematoma.  Hematomas in post op total knees can increase the risk of infection, can decrease range of motion, and cause pain which leads to immobility.  These are all risks for having post op complications or requiring further surgery to wash out the hematoma.  Icing 20 minutes on and 20 minutes off for the first 48-72 hours after a total joint replacement, or other orthopedic surgery is extremely important.  Ice is also great to use in the period immediately following trauma such as sprains, strains, contusions to decrease bleeding and edema (swelling).

Heat is great to use for more chronic-type pain. A lot of patients find it helpful to loosen arthritic, stiff joints, and also to relax muscles and decrease spasm.

Please take a look at the chart below and make sure to always follow the safety precautions when using heat or ice therapy!

**SAFETY TIPS

• Treat for no longer than 20 minutes at a time
• During ice treatment, check skin every 5 minutes to make sure the skin is not red or blistered, indicating freeze damage
• Do not place ice or heat directly on the skin, use a thin towel in between
• Do not lie on a heating pad or fall asleep using one to prevent burns
• Do not use heat or ice if you have no feeling in that part of the body
• Never use heat if you have swelling or bruising