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By: Dr. Paul J. Mackarey

This column is a monthly feature of “Health & Exercise Forum” in association with the students and faculty of Geisinger Commonwealth School of Medicine (formerly The Commonwealth Medical College).

Heat vs. Cold

Guest Columnist: Kevin Perry, MD

“Should I use heat or ice?” Several years ago, while working as a third year medical student at TCMC on orthopedic rotation, I was surprised to find that this is one of the most common questions asked by weekend warriors trying to relieve shoulder pain after playing tennis for the first time in 6 months. Now, as an orthopedic resident, the frequency of this inquiry has not changed. Trying to decide whether to use ice or heat to make it feel better and heal faster may not be so easy. Unfortunately, there is confusion, even among medical professionals, about the appropriate times to use  heat or cold. However, if we review the basic science on this subject, there are some valuable guidelines to consider.

The Science

When an injury is sustained, such as a sprained ankle, chemical signals are released in the area of the injury, which increases blood supply to the damaged tissues to allow appropriate cells to repair the damage. This response is evident by the principle signs and symptoms of inflammation including heat, redness, swelling, pain, and loss of function. This reaction makes sense because anytime tissues are injured; the body is responsible to protect the site until repair can occur. To protect the injured site, the body causes swelling and pain to prevent excessive movement or overuse which will lead to further injury. With the site of injury protected, the appropriate cells are able to lay down new tissue to repair the damage. As tissues heal, a web of connective tissue pulls the damaged tissues back together and holds them in place while new tissue is formed. Once the tissue is completely repaired, the blood flow returns to normal and fluid drains from the site of injury allowing restoration of motion and function. However, the new tissue is fragile and unorganized and often sticks together leaving tightness and weakness. After repeated use, the new tissue adapts to the stress placed upon it and becomes functional.

The Application

When grounded in science, the use of heat or cold can be used to expedite the healing process. While inflammation is crucial to the repair of injured tissue, the response can be exaggerated and last longer than necessary. Therefore, ice and heat can be used to modify the bodies’ inflammatory response and help us return to activity sooner.

How Cold Works

Ice causes blood vessels to narrow and nerves to slow down. When ice is applied to tissue, the body responds by decreasing blood flow to the area to preserve the core body temperature. Also, as nerves cool down, the signals they send slow down and become less frequent, so the pain signals they send to your brain become less intense. Thus, we can use ice to decrease blood flow to inflamed tissue which will reduce swelling and decrease pain. Ice is ideally used immediately following most injuries to control pain and swelling.

How Heat Works

Heat causes your blood vessels to open and increase blood flow to tissues. When heat is applied, blood flow and tissue temperature are increased and tight tissues relax and are better able to glide across one another. However, when applied too early in the healing process, heat, by increasing blood flow, can increase swelling and pain. Heat is ideally used after an injury has healed and there is residual tightness or protective muscle spasms. 

Now that we know how ice and heat work in conjunction with the inflammatory process we can easily understand when to use each one. Ice is best used following an acute injury. For example, ice is effective day one through three following an ankle sprain, or until swelling is controlled. Anytime the principle signs and symptoms of inflammation are present, ice is the appropriate treatment of choice. Regardless of when the injury occurred, if there is swelling and pain, ice is the appropriate treatment.   Heat should be used when there is tightness and stiffness and no signs of acute inflammation. For example, week two of three, following an ankle sprain if stiffness persists and swelling is controlled.

How To…

Apply ice using a bag of ice and water, ice pack, or bag of frozen vegetables wrapped in a wet towel. Cover the injured and swollen area and if possible elevate the iced area above the level of your heart. You should apply ice for a maximum of 20 minutes and rest at least one hour between icing sessions so as not to cause harm. Never apply ice directly to skin and never fall asleep while icing.

Apply heat with a heating pad covered in a few towels or warm a bag of rice in a microwave. Cover in a towel and place the heat on the affected area for a maximum of 20 minutes and rest at least one hour between heating sessions. Never apply heat over skin that you cannot feel (numbness or loss of sensation) or on open wounds in the skin. Also, do not lie directly on the heating source and don’t fall asleep while using heat to avoid burns.

Hopefully this information is helpful in dispelling some of the confusion regarding when to use ice or heat. As you can see there is no “golden rule” or “72-hour rule” for advising when to use ice or heat. But if you stick to the principles discussed in this article, you should be treating your aches and pains appropriately. This has been a simplified explanation of a complex topic and if you have any further questions, please ask a medical professional.

Top Reasons for use of Ice (Cryotherapy):

Top Reasons for use of Heat (Thermotherapy):

  • - Chronic Stable Low Back Pain  (Example: Healed Lumbar Strain)
  • - Postural Neck Pain (Example: Trigger Points)
  • - Prior to exercise/activity (Example: Rehabilitation)
  • - Osteoarthritis with stiffness (Example: Morning stiffness)
  • - Muscle Spasms (Example: Overuse)

Kevin Perry, MD graduated from The Commonwealth Medical College (GCSOM) in 2015. He is a resident in Orthopaedic Surgery at LSU Health Science Center Shreveport and will be moving back to Pennsylvania next month to pursuit a fellowship in orthopedic trauma at Penn State Health Milton S Hershey Medical Center. His special interests include pelvis and acetabulum trauma, complex periarticular fractures, malunions, nonunions, and deformity correction. Dr Perry completed his undergraduate education at Loyola University Maryland and graduate degree (doctor of physical therapy) at the University of Scranton.

Read all of Dr. Mackarey's articles in the Health and Exercise Forum at our website:

Read “Health & Exercise Forum” – Every Monday.  This article is not intended as a substitute for medical treatment. If you have questions related to your medical condition, please contact your family physician. For further inquires related to this topic email:

Paul J. Mackarey PT, DHSc, OCS is a Doctor  in Health Sciences specializing in orthopaedic and sports physical therapy. Dr. Mackarey is in private practice and is an associate professor of clinical medicine at GCSOM.