How to Correctly Use Cold & Heat Packs, According to a Doctor

Imagine you've got a strain or a sprain, or you've pulled a muscle and need some do-it-yourself pain relief.

Heat packs and cold packs can offer relief, but choosing between the two can be baffling. Which will be best for your particular pain?

Dr. Rajiv Bahl, an emergency medicine physician in central Florida, breaks down when to use a cold pack and when to use a heat pack so you'll never be confused again.

Cold packs

What is a cold pack?

To make your own, place a wet towel in the freezer for 15 minutes, then put it in a plastic bag. Or fill a zip-close bag with ice cubes, Johns Hopkins Medicine suggests. A bag of frozen peas or carrots also serves the purpose. There are also disposable and reusable products you can buy and store in your freezer.

Some cold packs require no freezing or refrigeration, but their cold temperature typically lasts no more than 20 or 30 minutes. You can find them at pharmacies and other online or brick-and-mortar stores.

Always insert a barrier between you and the ice or other product. A simple towel around a cold pack protects your skin.

How do cold packs work?

"Cold therapy reduces blood flow to the area, decreasing inflammation,” Bahl said. Inflammation -- in this context -- refers to swelling that you can see. For example, if you sprain your ankle, it may swell. That’s visible inflammation.

When should you use a cold pack?

“Cold packs are appropriate for recent acute injuries,” Bahl said.

The American Academy of Orthopaedic Surgeons (AAOS) says the following injuries can benefit from cold packs:

  • Bruises, if the injury doesn’t result in a broken bone
  • Sprains (a stretched and/or torn ligament, tissue that connects your bones), including sprained ankles, knees and wrists
  • Strains (a stretched or torn muscle or tendon, a cord that attaches your muscles to your bones), including a strained leg or elbow

How to use a cold pack

Gently apply the cold pack to the injured area. Remember to wrap the pack in a towel to protect your skin.

Cold therapy is often the first response to an acute injury, Bahl said.

“Cold packs are easy, topical [they go on the surface of your body] and cost-effective,” he noted.

When should you not use a cold pack?

If your symptoms don’t ease after you take over-the-counter pain medications, drop the cold pack and go to the emergency room. "You may need image tests that reveal the underlying reason for the pain," Bahl said.

Heat packs

What is a heat pack?

Bahl prefers to call these "warm packs," not heat packs, noting that some people misinterpret heat as "hot" and end up hurting themselves.

Heat therapy is delivered through heating pads, heat lamps and warm baths. Heating pads are commonly used as heat packs.

How do heat packs work?

Maintaining adequate blood flow to the injured tissues is important for healing, according to the University of Rochester Medical Center in New York.

“While cold packs decrease blood flow to a specific area, heat increases it,” Bahl said.

When should you use a heat pack?

Generally, Bahl said, “cold packs are needed for sudden acute injuries while heat packs are reserved for chronic [long-lasting] injuries and/or pain.”

Heat is best for:

  • Injuries caused by sudden movement
  • Injuries caused by twisting
  • Muscle pain
  • Muscle stiffness
  • Anytime you’re not able to use your full range of motion.

“Heat therapy increases muscle flexibility, decreases muscle pain and relaxes your muscles,” Bahl said.

How to use a heat pack

If you’re using a heating pad, put it in a pillowcase or wrap it in a towel to protect your skin.

Take a bath in warm water, not hot.

Don’t fall asleep under a heating lamp or with a heating pad turned on -- you could burn yourself.

When should you not use a heat pack?

Bahl warns that you should never use a heat pack on burned skin. Adding heat to even a first-degree burn could cause more damage.

SOURCE: Rajiv Bahl, MD, central Florida emergency medicine physician

What This Means For You

Heat or cold can provide relief after an injury but knowing which is best for your particular injury is key.