Is it Better to Use Ice or Heat?

  • You just crushed that workout!

  • You just hit the send button on that work email!

  • You just got the kids bathed and into bed!


Now you can relax… except you can’t. Your neck hurts, your knees hurt, your back hurts. Is it better to use ice or heat?

Quick, grab the ice pack. Wait! No, grab the heating pad. Now you can’t remember. You definitely don’t want to make this pain worse.

What do you do?

As a Physical Therapist I get asked this question all of the time. Whether I’m at work, in the gym, or talking to my friends and neighbors, people never seem to remember which thermal modality they should use.

This article is here to help you make the right choice, but first…

It is useful to understand two things:

  1. What happens (in general) when your body gets injured?
    • When you first sustain an injury, we call it the Acute Phase. This generally lasts 0-4 days but can vary depending on the injury.
    • Blood vessels local to the injury dilate or open up to allow increased blood flow. The purpose is to bring more blood/nutrients/healing factors to the injured site. It is a normal and necessary part of the healing process.
    • A side effect of this is edema, or swelling (which in itself can cause more pain).
  2. How does ice or heat affect this process?
    • Ice and Heat are referred to as thermal modalities.
    • They have significant affects on soft tissue, blood vessels, and nerve conduction.
    • They are underrated tools for facilitating healing and pain control, you just have to know how to use them.

When is it better to use ice?

Short answer: When you first get injured or after a specific event that leads to pain.
  • Ice will do two things. First it will control/limit the swelling.
  • Second, it will decrease pain according to the ‘Gate Control Theory’.

How does it control swelling?

Our blood vessels are made of smooth muscle. That is, they have the ability to contract and relax. And as it turns out, they behave the same way that we do when it comes to temperature changes.

Step into a snowstorm with no jacket and you immediately draw your arms in, hug yourself and try to conserve warmth. Your blood vessels will act the same way when you apply an ice pack.

This is useful during the acute phase because it limits (but does not stop) the amount of excess blood flow to the injured tissue. This will control the swelling and prevent further pain.

What is the ‘Gate Control Theory?’

Imagine a nerve route from your area of injury to the brain, where you would feel the pain. There are two types of nerve fibers that carry the ‘pain signal’. They are ‘A-Delta’ fibers and ‘Type C’ fibers.


Note: You can see on the graph that A-Alpha and A-Delta nerves conduct signals to the brain the fastest.

These are responsible for Proprioception (awareness of body in space) and touch, respectively.

Courtesy of The Brain From Top To Bottom.

  • A-Delta fibers have faster conduction and are active when you first get injured. When you roll your ankle, the A-Delta fibers let your brain know there is an intial injury and that that it hurts.
  • Type C fibers are slower and transmit the continuous pain signal after the initial injury.

Gate Control Theory in its simplest form states that you can ‘shut the gate’ along that nerve route and stop the pain signal from reaching the brain.

Ice is one proven way to ‘shut the gait’. Temperature change is sensed by the A-Delta fibers, which are faster that Type C. So the sensation of cold races ahead of the sensation of pain and shuts the gate before it can reach the brain.

When is it better to use heat?

Short answer: When you are out of the acute phase or when the injury is chronic.
  • Heat will also do two things. Firstly it dilates your blood vessels, increasing blood flow to and through the area it is applied.
  • Second, it relaxes and eases tension in the soft tissues around the painful area.

I thought the purpose of ice was to control the swelling, won’t heat do the opposite?


It is true that heat will open the blood vessels and therefore increase blood flow to the injured area. This is beneficial after the acute phase of injury.

  • Remember that the acute phase begins at time of injury and can last up to 4 days. During this time the body is shunting blood directly to the injured tissue in an effort to heal it.
  • After the acute phase passes, this redirection of blood is stopped (or significantly decreased towards normal levels), but now we have an excess accumulation of fluid, broken proteins, and other cellular debris at the site of injury.
  • Applying heat will open the blood vessels and allow all of this extra swelling and debris to be ‘washed away’ back into circulation.

Will it help with the pain?

Yes! In two ways.

  1. The washing away of the debris and swelling will decrease pressure on the injury site. Decreased pressure generally means decrease in pain.
  2. Heat will allow all of the surrounding tissues to relax.
    • Part of the initial protective response during injury is for the muscles to contract and be ‘on guard’ against further insult.
    • This protective state can persist either due to physiological reasons, or due to general apprehension from the person. When this happens we are at higher risk for chronic pain.

How do I know if I’m applying heat too early?

Quite simply, your swelling will increase instead of decrease and you may experience an increase in dull or even throbbing pain.

But don’t stress too much. If this happens, it does not mean that you have done any extra damage. It just means you jumped the gun a bit and should switch back to ice for the time being.

Below is a fantastic visual guide from OrthoCarolina:


By now you should have a better understanding of when to use ice versus heat. Hopefully you also know how and why each of them works.

If you’re like me, knowing how a tool works guides me to know when is the best time to use it.

Speaking of tools, here are some options for excellent ice and heat packs.


These are FANTASTIC and very similar to the kinds used in outpatient therapy clinics.

They get cold and stay cold, and you can wrap them around your limb.

Get them from here at Amazon.


When looking for your heating pad, you want adjustable settings, a flexible surface, and an automatic shut-off.

My Wife and I often fight over who gets to use this one!

If you are currently dealing with back pain (possibly as a result of the new work-from-home economy that COVID has necessitated), you might be able to fix it your self after reading 5 Proven Ways to Relieve Sciatica Nerve Pain.

Or if you are lucky and don’t have any pain to speak of, keep it that way by reading 7 Best Ways to Stay Healthy Working From Home.

If there is an issue that you have questions about, email me at I’d be happy to help.

And I’d be super grateful if you would take a couple of precious seconds to follow my blog. It really does mean a lot to me.


Dan Kristoff PT, DPT is recognized as one of the Top Physical Therapists in Ohio. In his 10+ yrs as a physical therapist, he has helped thousands of patients recover from illness and debility. His company, Rehab Revolution, is less than a year old and has already helped hundreds of clients take back control of their health.

Published by Dan Kristoff PT, DPT

President of Rehab Revolution Creator of CleBD Topical and Doctor of Physical Therapy

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