When to Use Ice for an Injury and When to Use Heat

This post is part of our Home Remedies Guide , a review of home remedies from dubious to doctor-approved. Read more here .

Hot compresses and cold compresses are some of the most useful and convenient tools for dealing with pain in certain parts of the body. But when should you use each one?

Ice is commonly used for minor injuries such as ankle sprains and muscle strains, but you may have heard that it is no longer recommended as much as it used to be. Many of us have learned that injuries should be referred to as RICE: Rest, Ice, Compression, and Elevation. But in recent years, you may have heard more about its opposite, MET: move, lift, pull, heat.

In truth, there are good times for ice and good times for heat. Let’s take a look at what each one does and look at a few rules of thumb to help you decide which one to use.

Why do you have swelling and inflammation after an injury

When you receive a sudden injury, such as an ankle sprain, your body starts a process called inflammation. The inflammation causes the damaged area to become red, swollen, hot, and very painful. It’s not fun, but that’s how the healing process begins.

The edema brings additional immune cells to the area to begin repair work. The swelling can also make a part of the body stiff, which can be somewhat helpful in protecting that area. And pain can cause you to naturally give the injured area some rest.

But that doesn’t mean inflammation is always good. If the swelling is severe, it can cause more damage. And while pain may prevent us from using the injured body part, we are usually happier if we can take the edge off the pain and simply not use that body part anyway.

What happens in your body when you apply ice

Ice reduces many of these aspects of inflammation. It dulls the pain, and frankly, the main reason we use ice for injuries is because it’s a cheap, quick, and easy form of pain relief. This prevents your body from swelling the tissues as much as it would otherwise and can reduce the formation of bruises and bruises (blood clots in the tissues).

In the first few hours or days after an injury, ice can help control this potential overreaction . Your ankle may heal well with little swelling; it doesn’t necessarily require as much of a tumor as your overzealous immune system might want you to.

Of course, ice has its drawbacks. Once the injury is over and the swelling has subsided, you don’t want to interfere with your body’s healing processes. Ice can also increase the pain of some injuries, especially muscle soreness, cramps, or knots. This tends to increase stiffness and muscle spasms.

You also need to be careful with ice. Cooling area is good; give yourself frostbite is not. A good rule of thumb for when to take a break from an ice pack is, “When you’re numb, you’re done.” If the skin is numb, remove the ice pack for about 20 minutes. Never let yourself fall asleep with an ice pack.

What happens in your body when you apply heat

The effects of heat are, unsurprisingly, the opposite of ice. Heat dilates blood vessels and increases blood flow, so if you apply heat to an ankle sprain, you can increase swelling and possibly make the injury more painful.

But after that initial inflammation (or after an injury that has come on gradually and hasn’t gone through that stage), heat can be helpful. Increased blood flow may promote healing. This is where the acronym MET comes in: movement and heat are especially helpful in moving blood and nutrients to where they need to be, as well as keeping the injured body part from becoming too stiff or painful while it heals.

Heat can also reduce soreness and stiffness from muscle injuries. If your back muscles are sore after a heavy deadlift workout, the warmth will feel good on your back. If you wake up with a crunch in your neck and stiff neck muscles, the warmth will likely provide some relief.

How to know what to use

One rule of thumb is that ice is used for the first 24 (or 48 or 72) hours after an injury, and then heat is better. This is a good rule, but there is a caveat.

First of all, how long is that initial period when you have to freeze it? It will depend on the injury. For some, it’s only a few hours. For others, especially those with more severe injuries, it can actually last several days. A good way to determine this is to ask yourself if the injured area is red, hot, unusually swollen, and in pain. If yes, then it’s ice time. If not, you can probably move on to heat.

Another important factor is what kind of pain or injury you are dealing with. Injuries that respond well to ice are usually acute tissue damage: something is torn, broken, or pulled. Those that respond to heat are more likely to be chronic or aching pains, or those associated with spasms or cramps. A few examples:

• Recently stretched or torn muscle : ice because it is an acute injury.
• Recently sprained ankle or other joint : ice, same thought.
• Severe recent bruising : Ice to reduce swelling and reduce the chance of a large hematoma (clot) forming.
• Sore muscles after a workout : warm to relax and soothe them.
• Muscle spasms or convulsions : fever – the same.
• Trigger points or knots in the muscles : fever. We don’t really know what knots are , but most people feel worse with ice and better with heat.
• Back pain : often responds better to heat because it is usually associated with muscles.
• Anything sensitive, hot, red, or swollen : ice to relieve inflammation.

As a very general rule, you can go with your intuition. When my back muscles hurt after a workout, I want nothing more than to plunge into a hot bath. You couldn’t pay me to freeze them.

By the way, all these tips are for minor pains. Sometimes injuries can be more complex than what these simple rules explain. And if something is seriously wrong, or if you suspect it is, be sure to contact a professional and follow their instructions. You don’t want to sit and put ice on a sprained ankle if it really could be broken.