It’s one of our most frequently asked questions. For muscle and joint pain, what’s best—heat or ice? As in much of medicine, the answer—it depends.
First, it’s important to make the distinction between treating the problem and the symptoms. For the most part, heat and ice work on symptoms. It’s been studied and some research suggests a therapeutic benefit, but those results are very limited and not well established.
Neither will do much to mitigate the cause of the pain. But for a pulled muscle, back spasms, twisted ankle or soreness after intense activity—ice or heat can help you feel better. And there’s a third option: nothing. Sometimes it’s best to just leave it alone.
Let’s break it down.
It’s all about blood flow
Ice causes vasoconstriction. The blood vessels tighten up and get smaller, reducing blood flow. Heat has the opposite effect, dilating the blood vessels to increase blood flow.
Generally speaking, when pain comes with inflammation, usually evident with swelling, ice is the way to go. The classic example, a sprained ankle that swells. Ice is the best choice for any injury that causes swelling, especially in the short term. I consider ice part of first aid, for injuries that cause trauma or cellular damage, like strains, sprains and bruises.
In addition to reducing inflammation, ice is a natural painkiller that can numb the problem area. A good rule of thumb: sharp, intense pain takes ice—typically in the earliest phases. Dull, achy pain does better with heat. After that initial trauma, using ice can be detrimental. You need blood flow for healing, so we don’t recommend ice once the initial injury starts to feel better and moves from sharp pain to sore.
You have to be careful with both. Ice can freeze the flesh, causing frostbite if it’s left on too long. Then you’re in a situation potentially more dire than the original injury. In addition to frostbite, ice exposure can send the muscles into spasm, creating a new set of problems.
- Maximum safe exposure is 20 minutes, so I tell my patients to go 15 to add a cushion of safety.
- Don’t put ice on bare skin, protect it with a towel or clothing.
- Set a timer, you probably have one on your phone. You can hurt yourself if you accidentally fall asleep with ice; the timer will keep you safe.
- Leave ice off for at least 20 minutes before reapplying.
- Continue the 15 minutes on/20 minutes off cycle, two to four times each day.
- Don’t use ice for more than three days.
Heat for older injuries
I recommend heat more often than ice—since most of my patients are dealing with pain over the long term. Heat is appropriate for an older injury, regular soreness, dull ache, cramps and stiffness. When muscles are tight, heat can loosen things up and make it feel better. Again, you have to be careful. Too hot a temperature or too long exposure can cause a burn injury.
I’m partial to microwavable heat pads. The ones you buy are generally filled with cherry pits, which get very hot with microwave energy and hold onto heat for some time. If you’re good with a sewing machine, you can make your own pad, filled with rice.
But you don’t need a purpose-built pad. It’s simple to improvise:
- Wet a towel and wring it out so it’s damp but not dripping.
- Fold or roll it up.
- Microwave 30-90 seconds until it’s warm, then carefully apply it to the problem area.
If it’s too hot, let it cool a moment to prevent a scald. Every microwave is different so you may need to experiment a bit until you hit the target.
Microwave heat offers a margin of safety; the pad gets good and hot, but the heat dissipates over time, so you’re unlikely to hurt yourself with long-term exposure. Electric heat pads stay hot as long as they’re plugged in, so the margin of error is slimmer, especially if you get distracted or fall asleep. Compared to ice, a microwave heat pad is very safe. You can’t do any real damage with it as long as you don’t burn yourself.
Occasionally, I’ll recommend alternating heat and cold over 10-minute intervals. It creates a pumping effect, slowing blood flow, then speeding it up. It is helpful in certain situations—but it’s trickier to manage and for a narrow set of circumstances. It’s best to follow this protocol with supervision.
Leave it be
“Neither” is also an option. Remember, both ice and heat work on symptoms, they don’t have a significant effect on the cause of the discomfort. If the injury isn’t debilitating and not getting in the way of your activities of daily living, you don’t need heat or ice, just let nature take its course and the body will heal.
As long as you use ice or heat safely, it’s a matter of doing what feels best. But if you’re unsure—ask your provider, especially if you have any underlying conditions.