Should You Use Heat or Ice for Acute Pain?

Read on for tips on when to choose heat and when to choose ice for acute pain. And be sure to see your doctor if the pain is severe, you can’t put any weight on the injured area, or you have progressive numbness or weakness, says Bryan Marascalchi, MD, an anesthesiologist and pain medicine specialist at Vanderbilt University Medical Center in Nashville, Tennessee.

Doctors typically recommend using ice to help ease pain. There’s even an oft-used acronym: RICE, which stands for rest, ice, compression, and elevation. Applying ice to acute pain can help relieve discomfort by minimizing swelling, reducing inflammation, and numbing the affected area. Icing an injury can help it heal faster, too, and continue to ease pain a week or two after you first experienced the ailment or injury.

Injuries and Ailments to Ice

Ice is recommended for the following injuries and ailments:

• Swelling or redness from a new injury, such as a strain, sprain, pulled muscle, or bruise
• Pain after a fall or impact, such as a bump on the head or a finger caught in a door
• Acute pain due to overuse or tendinitis, as from a flare or shin splints
• Pain and pressure from a fever, headache, or migraine
• Pain from a cut or scrape
• Pain after surgery or an injection, if approved by your doctor

When to Apply Ice

When it comes to icing an injury, don’t delay. “The best time to use a cold pack or ice is immediately after the injury, because your goal is to decrease inflammation. And getting inflammation under control early on will help speed along your recovery and get you mobile faster,” says Michael Richardson, MD, a family medicine physician and expert in men’s health, sports medicine, and fitness in Wellesley, Massachusetts. For a typical strain, sprain, or overuse flare, cold packs should be started as soon as practical, especially in the first 24 to 48 hours, when pain and swelling tend to be most active. “[That’s] when the swelling and inflammatory process is being unleashed,” says Douglas Chang, MD, PhD, a physical medicine and rehabilitation specialist and professor of orthopedic surgery at the University of California in San Diego School of Medicine.

But it’s not an all-or-nothing situation. Ice can still help later for pain after activity or rehabilitation sessions.

How Long and How Often to Apply

To effectively use cold for acute pain, regularly apply it, and monitor your pain level. “Apply ice for 15 to 20 minutes at a time — once or twice an hour, while awake, in the first 12 hours and then about every other hour after that,” says Dr. Chang. You can repeat the use of ice “every few hours, as needed, during the first couple of days,” says Dr. Marascalchi. “Continue as long as it meaningfully reduces pain or swelling, and then taper.”

How to Use Cold for Acute Pain

When using ice to ease pain and swelling, be sure to protect your skin from frostbite by placing a thin barrier, such as a washcloth or paper towel, between the ice and skin, says Chang. “It’s important not to have it too cold, so it doesn’t damage the surrounding tissue,” says Dr. Richardson.

As for which kind of ice pack to pick, the choice is yours. Commercially made versions are fine (you may have several in your freezer right now from past summer picnics), or simply place some cubes in a resealable bag with a bit of water. Richardson suggests making the homemade pack with crushed ice, water, and salt. “The salt will lower the freezing point of the water and allow the water to be colder in liquid form. And the crushed ice gives you more uniform cooling across a larger surface area, compared with a solid block of ice.”

You can also grab a bag of frozen peas or corn, as these options “conform nicely to the body part,” says Chang. But skip a frozen ribeye, says Richardson. “Leave steak in the freezer, and instead go with that bag of peas. It’s flexible, it covers more area, and it’s a lot more hygienic.” For headaches, a cold wrap or mask can be positioned around the eyes, face, and neck for relief.

Precautions With Ice

Ice is a simple, effective treatment for acute pain, but there are some instances where it’s not recommended. For example, “You wouldn't necessarily use it prior to a workout,” says Richardson. Any stiffness you feel before exercising may only get worse with ice.

Chang recommends not using ice (or stopping the application of it) if any of the following is true:

• Your skin becomes white, painful, or numb.
• You have a skin infection.
• You have circulation problems, nerve damage, or a history of neuropathy, such as from diabetes.

And if you’re using ice for knee pain, “Don’t put ice over the outer side of the knee,” says Chang. “Icing there can inadvertently affect the peroneal nerve and cause a few weeks of foot drop,” which is weakness in the muscles on the top part of the foot that’s usually due to nerve compression.

Heat helps acute pain by loosening sore muscles and joints and bringing blood flow to the affected area to ease stiffness and spasms. “Heat is typically more useful once swelling has settled and the main issue has become stiffness, muscle spasm, or limited range of motion,” says Marascalchi. “Heat increases local blood flow and tissue pliability, which can make stretching and movement easier.”

Types of Injuries and Ailments to Treat With Heat

Heat is recommended for the following injuries and ailments:

• Muscle tightness or spasms due to knots or tension
• Stiff joints caused by arthritis, osteoarthritis, or tendinosis
• Aches from muscle overexertion or poor posture
• Tension due to headaches or neck and shoulder tightness
• Menstrual cramps that affec the belly and lower back
• Muscle soreness after exercise

When to Start Heat for Pain

Timing is everything when it comes to starting heat for pain. Specifically, you should begin using heat 48 to 72 hours after the injury. “At this point heat helps, because it dilates the blood vessels, increasing circulation, relaxes tight muscles, and reduces joint stiffness,” says Chang.

Heat should never be applied right after an injury or the onset of pain. “If heat is applied early, within the first 24 to 48 hours, it will increase blood flow and accelerate the inflammatory cascade, which leads to more swelling, worsened pain, and a delayed recovery,” he says.

How Long and How Often to Apply Heat

As with ice, short applications of heat are best. Use heat several times a day, for about 15 to 20 minutes at a time, so the injured area can cool off (about an hour is fine between sessions).

How to Use Heat for Acute Pain

A classic plug-in heating pad is a common option for soothing pain, but be very careful not to use the highest setting for too long, due to the risk of potential burns. Warm compresses, microwavable heating pads, and hot water bottles are good picks for sore muscles. Heat wraps can be laid around the neck and shoulders, targeting these hard-to-reach areas.

Moist heat, including a warm towel, shower, bath, or reusable hydrocollator (temperature-controlled water bath), is also ideal for relaxing and soothing aches. As for when to use moist over dry heat, experts say it depends on your goal. “With moist heat, you’re going to cover more surface area on your skin and have stronger contact than with dry,” says Richardson.

“Moist heat heats the tissue somewhat faster, because water conducts heat better than air,” says Chang. “It also usually feels more soothing,” though it cools more quickly and is more messy and less convenient than dry heat, he adds.

Precautions With Heat

When taking a bath or shower, be sure to keep the water temperature between 92 and 100 degrees F for safety. That’s the sweet spot for soothing without scalding.

And don’t let a heating pad or hot water bottle touch your skin directly. Instead, put a thin cloth barrier between the two.

Use a timer, so you don’t overdo it. Dozing off in a tub or in bed with a heat source may be tempting, but it’s a burn risk.

Remember the importance of skin protection. “Avoid heat on open wounds, areas of impaired sensation, or where you can’t reliably monitor skin temperature,” says Marascalchi. “As with ice,” says Chang, ”don’t use heat with a skin infection, nerve damage to the area, circulation problems, or neuropathies like from diabetes.”

Lastly, don’t opt for heat with a new injury (that’s what cold is for) or on a swollen or red body part, because this worsens inflammation.

• Ice or cold can help ease the pain of new injuries and reduce swelling when applied right away or within a day or two.
• Once the swelling has subsided — after about three days — you can apply heat for stiffness, soreness, and muscle tension to relax tightness and enhance mobility.
• Ice and heat have their uses for everyday discomfort, but if the pain is severe, you can’t put weight on the area, or you have numbness or weakness, it’s best to check in with your physician or urgent care.