How to reduce swelling from an injury: When to ice & when to heat?
Dr. Grant Lipman
Grant S. Lipman, MD, is a clinical assistant professor of surgery in the division of emergency medicine at Stanford University and associate director of the wilderness medicine fellowship at Stanford University School of Medicine.
Sprains, strains and muscle pulls are common injuries in anyone’s body. Knowing how to reduce swelling from an injury can go a long way in reducing the amount of time laid up on the couch recovering. Injuries like those can happen to anyone, but what should you do if you injure yourself with limited supplies in the backcountry? Spraining an ankle on unsteady scrambles, pulling a muscle while lifting a heavy pack, or simply putting your body under strenuous conditions are all possible in an outdoor activity.
Our medical advisors know the science of injuries and how — scientifically — ice and heat help us heal.
How heat and ice reduce the swelling of an injury
Direct injuries, such as an ankle sprain, will often become tender and swollen. Inflammation is how our body responds to the injury — by increasing blood flow to the injured area. The reason why we use cold and heat treatments for injuries is to control this blood flow.
When our skin is exposed to cold, our bodies are genetically programmed to conserve heat. This helps us from becoming hypothermic or freezing to death, when we are caught outdoors. When something cold like an ice pack is applied to an area of our body, it makes the blood vessels shrink down and decreases blood flow to that region. This decreased blood flow then helps reduce inflammation and swelling.
Heat treatment does the opposite, opening up blood vessels in the area and increasing blood flow to the region. This is helpful in promoting healing a little after the acute phase of injury (i.e. the worst phase of inflammation). Heating or icing an injury comes down to timing.
🧊 Ice First
Icing or cold therapy is generally useful to reduce swelling from an injury — soon after the acute phase of injury which is considered the first 72 hours (three days).
At home, you can use:
- A cold compress (gel pack kept in the freezer)
- Ice pack (like you would put in a cooler or lunchbox)
- Ziploc bag of ice
- Bag of frozen peas, if you got ‘em
Avoid putting ice directly on the skin. It’s best to have a layer between your skin and the ice (like a shirt or dish towel).
If you’re away from home and need to improvise an ice pack in the backcountry, here are some methods:
- If you’re camping with a cooler, a chilled beverage could be used as an ice pack.
- If you’re near a body of water, submerging the injury in the cold water could help “ice” it.
- If there’s snow around, you can use that! Similar to ice at home, be careful not to place the snow directly on your body, as you could freeze the surface of your skin (i.e. frostbite).
How long should you ice?
Ice the injury just until the area feels slightly numb, but not painful. Generally, 20 minutes per session is a good benchmark.
Injured your ankle on a hike and need to reduce swelling? Submerging the injury in a cold body of water can help reduce the inflammation.
🔥 Heat Later
Heat helps to aid recovery after the worst of the inflammation has passed (beyond 72 hours).
At home, you can use:
- A heating pad (there are many varieties, such as electric plug-in or microwavable)
- Old school hot water bottle
- A small towel soaked in hot water
- A sock filled with rice, microwaved for 30 seconds
None of these should be so hot that they burn the skin. If it feels too hot, put a layer between your skin and the heat (like a shirt or dish towel).
Away from home? Here’s how to improvise a heat pack in the backcountry:
- Heat up some water (not boiling), and fill a heat-safe water bottle
- Pack store-bought hand warmers
- Allow the area of the injury to rest in the sun (using sunscreen, of course).
Sometimes conditions and limited supplies can make creating a heat pack difficult, but heat therapy is less important than cold therapy. In many scenarios you can always choose to end a trip early and return home before the 72 hour window passes.
Do pain relief patches reduce swelling from injury?
There are several types of over-the-counter patches to treat minor pain. You’ll notice they might have different active ingredients such as menthol (often sold as IcyHot), camphor, and capsaicin.
These patches work by stimulating the nerve endings in your skin, effectively ‘distracting’ your body from the pain. While some studies suggest that they may have mild anti-inflammatory properties, it’s best to think of these as solely treatments for pain and not a complete fix for the underlying injury.
If pain relief is your main goal, patches are worth a shot! Just don’t use these products on open skin or burned areas as they may prevent the skin from properly healing.
To sum it up:
Ice early after an injury and heat later on, after 72 hours post-injury.
Discover more improvised first aid methods for injuries head-to-toe when you’re away from resources. Browse the Wilderness Medicine Library in our GOES Health app.
