Hot or Cold? Deciding Whether to Use Heat or Ice.

You hear a pop in a joint, or feel a wrench in your back, and immediately your mind starts running through the options. Heating pad? Ice pack? Can you treat this yourself, or is it time to see a physical therapist? Here are some guidelines to help you decide.

When to Reach for Ice

Ice is the best choice immediately after an injury. It works as a vasoconstrictor, meaning it narrows blood vessels, which keeps damaged, inflamed tendons and muscles from swelling too much and further restricting normal blood flow. Our physical therapists recommend icing an injury or sprain every 1 to 2 hours for the first 48 hours, and elevating the injured area above your heart while you do it. Cooling the area also reduces inflammation, decreases soreness, and supports healing, which is why you’ll see baseball pitchers and quarterbacks icing a shoulder or elbow after games. Ankle sprains, knee injuries, shin splints, and plantar fasciitis all tend to respond well to ice. That said, elderly people, young children, and people with diabetes should be especially careful with cold treatments, so check with a healthcare provider if you’re unsure.

You can ice an injury with a reusable ice pack, ice in a sealed plastic bag, or even a bag of frozen peas or corn. To make your own reusable pack, mix one cup of alcohol with two cups of water and freeze it in a freezer bag: the solution freezes at a lower temperature and stays more flexible around joints. Apply ice for no more than 20 minutes at a time, and let your skin return to room temperature before icing again. Always place a thin towel between the ice pack and your skin to prevent irritation or frostbite, and never ice before activity, since that can lead to further injury.

When to Reach for Heat

Heat relaxes muscles and loosens tissue, so it’s best used before activity, not right after a new injury. In fact, heat should never be used in the first 48 hours following a fresh injury. Chronic or long-term issues tend to respond well to heat instead, such as applying it to the quadriceps, a hamstring strain, or a low back strain before you get moving. Use a heating pad, heat compress, or hot, wet towel for no more than 20 minutes at a time, or take a hot bath before activity, and never sleep on a heating pad because of the risk of burns or fire. If an injury already feels warm or hot to the touch, don’t add more heat: reach for ice instead. Either way, avoid heat or ice over areas with numb skin or reduced circulation, and keep in mind that creams or lotions that create a hot or cold sensation don’t provide the same physiological effect as an actual ice pack or heating pad.

For a simple homemade heating pad, fill a cotton tube sock about three-quarters full with rice, beans, flax seed, or oats, then tie or sew the end shut. Heat it in the microwave on a plate for about 2 minutes, watching closely since it can catch fire if overheated. It will be very hot at first, so wrap it in a washcloth before applying it to your skin, removing the washcloth as it cools. It stays warm for about 20 minutes and can be reused many times. For minor everyday aches, heating before activity and icing afterward is often all you need.

When to See a Professional Instead

Watch for these red flags, which mean it’s time to see a doctor or physical therapist rather than keep treating things at home: pain that gets worse instead of better, pain that shows up after resting for a few days or when you wake up, chronic swelling in a joint or bruises that won’t heal, or a joint that locks or feels unstable. Trying to manage these issues at home with heat, ice, and anti-inflammatories alone can end up making the problem worse instead of better.