The fact is, it depends on the stage of the injury. So to say that using heat or ice to treat an injury is better or worse is inaccurate unless you’re speaking to when they should be used. Initially, when the injury is fresh, you will want to use ice. Applying ice to an injury will cause the blood vessels to constrict, reducing blood flow and reducing swelling. An ice pack will also serve as a local anesthetic, numbing the pain that you’ll be feeling from the injury.
Heat therapy is best for chronic injuries & ailments. If swelling and inflammation isn’t an issue, heat therapy is generally okay to use. If you have a chronic injury, applying heat will help loosen up your joints and muscles, increasing flexibility and reducing pain when you’re active.You Shouldn’t Put Ice on a Head Injury: MYTH
With concussions becoming a major concern in contact sports, some myths about head injuries have been floating around that are simply inaccurate. As far as hot and cold therapy is concerned, you should apply ice to a head injury. This serves the same purpose as any other injury—reducing blood flow to reduce swelling and inflammation, and also relieving the pain from the injury.
What you will want to avoid, especially if the head injury seems serious, is applying pressure to the injury. In the event that the skull has been fractured, applying pressure can further injure the area. Simply place and hold a cold pack on the injury don’t press it down.Only Keep Ice or Heat on an Injury for 20 Minutes: FACT
Icing or heating an injury for too long can cause further damage to the muscle tissue you’re trying to repair. If you ice an injury for over 20 minutes, you run the risk of frostbite or nerve and tissue damage. Your body will also try to counteract the cold and actually open the blood vessels up, which could increase swelling—the very thing you are trying to prevent. Heat application is a bit more tricky considering that it is used for chronic injuries. If you suspect you have a chronic injury (3+ months of pain), it’s important to visit a doctor that can instruct you on how to treat it.