I get this question all the time. “Should I use ice or heat for my injury?” It is almost instinctual to reach for heat, when you are in pain. Because it feels so good. But is that right thing to do? In most cases I would say NO. Both ice and heat will temporarily block the pain. But other than pain relief, they have opposite effects. Heat tends to increase blood flow and swelling and increase metabolic activity. While ice slows blood flow and swelling and slows metabolic activity. When you have an injury or sudden new pain, the body rushes in and tries to save the day by causing swelling and stimulating repair. This is good, but the body usually get a little over enthusiastic and does too much. One of the things it does is it stimulates the production of fibrin to repair the injury, but if you get too much fibrin you get too much scar tissue. Also, if the swelling is allowed to progress, it will amplify all the chemical messengers that cause inflammation and swelling and it will become a repetitive cycle that is hard to slow down. Heat exaggerates this cycle, whereas cold or ice slows it down.
This inflammation and swelling cycle can go on for a long time. One thing you often hear is to use ice for the first 48 and then use heat. I hear this all the time from patients who have gone to the ER, after a car accident. In general, I recommend that people use ice for most injuries 3 times a day for 15 minutes (not more), until the symptoms have calmed down. This can take weeks or months in some cases. I have had some patients ice for 3-4 months, after a whiplash injury or sports injury. The best ice pack is a bag of frozen peas. So, if you have had a whiplash injury from a car accident, don’t reach for the heat. Heat can be okay for chronic stiffness and tightness, but not for new injuries. I don’t recommend electric heating pads, because they create dry heat. Use a damp towel heated in a microwave for 1 minute on high. I’ll never forget a patient I had, when I first got out of school. She was an older woman who had used an electric heating pad on her back every day for 20 years. She had a large chronic muscle spasm that was almost impossible help, because the heat had caused scar tissue in the muscle. Ice rarely causes problems.
So, when in doubt, use ice.