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Health & Exercise Forum

Treating Injuries: Heat vs Cold

May 19, 2014

Dr. Mackarey's Health & Exercise ForumGuest Columnist: Kevin Perry, 3rd Year Medical Student The Commonwealth Medical College



“Should I use heat or ice?” While working as a third year medical student at TCMC, I was surprised to find that this is one of the most common questions asked by patients with musculoskeletal complaints. Trying to decide whether to use ice or heat to make an injury feel better and heal faster may not be so easy. Unfortunately, there is confusion, even among medical professionals, about the appropriate times to use of 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 warm, 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, therefore 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. Anytime the principle signs and symptoms of inflammation are present, ice is the appropriate treatment of choice. For example, immediately after spraining your ankle, if it is swollen and painful to walk, ice is the preferred treatment. 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 or three following an ankle sprain, if stiffness persists and swelling is controlled then heat would be beneficial.

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 a bag of rice heated 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):

  • Acute Injuries (Example: Sprained ankle)
  • Tendonitis (Example: “Tennis Elbow”)
  • Osteoarthritis with swelling (Example: Any swollen arthritic joint)
  • Following exercise to prevent swelling (Example: Rehabilitation)
  • Muscle Spasms (Example: Overuse)

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)

Guest Columnist: Kevin Perry is a third-year medical student at TCMC. Dr. Perry grew up in Wyckoff, New Jersey before attending Loyola University Maryland as a Biology major and Mathematics minor while competing as a soccer player. He continued his education at the University of Scranton where he earned a Doctorate in Physical Therapy, graduated with academic honors, and published research about the diagnosis of meniscal tears. After medical school, he aspires to complete an orthopedic surgery residency.

Read “Health & Exercise Forum” in the Scranton Times-Tribune – 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 The Commonwealth Medical College