Should I Use Ice or Heat on an Injury?

Q When should I use ice on an injury and when should I use heat? I get conflicting answers when I ask the question.



A Let’s start by taking a look at the body’s repair processes. Once an injury occurs, the repair process has three phases. The first phase clears the damaged cells, the second brings in the cells to form the repair structure, and the third does the finish work to give the cells the final structure and strength. In the case of a sprain, the damaged ligament tissue has to be removed, new fibrous cells moved in, and the new cells transformed into ligament tissue.

Swelling from tissue damage slows this process.

In the face of an acute injury, like an ankle sprain, ice works to keep the swelling down, which allows the injured parts to stay physically close in the repair process, promoting better healing. Heat, on the other hand, encourages blood flow and increases swelling in the acute phase. So, immediately following injury, heat actually harms the healing process.

But heat does have a place in chronic injury and after the acute phase of injury – it can relieve pain and loosen tissues. However, it’s not always easy to say exactly when heat is acceptable in injury care. I tend to stick with ice until all the swelling is gone and the pain is tolerable. Two to three days is probably a safe time period for ice, but holding off on heat and using ice longer does no harm.

Just remember, it’s critical to remove the ice before any tissue freezes. A reasonable cycle for icing an injury is 15-20 minutes on and 15-20 minutes off. Leave the ice on too long and you can damage nerves and other critical tissues. I had a patient who sprained his knee and decided to wrap an ice pack to the knee area while flying home from his game site. He fell asleep and when he woke two hours later, he had permanently damaged his peroneal nerve, leaving him with a foot drop and unable to play his sport. His athletic career was cut short by too much icing for an injury that would have healed well with conservative measures. Like everything, icing can be overdone.


About the Author
Dr. Roberts is a Professor in the Department of Family Medicine and Community Health at the University of Minnesota Medical School, U.S. He served as Medical Director for the Twin Cities Marathon and has authored many research and educational publications on sports medicine.

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