2 Reasons You Don't Want to Leave a Heating Pad on a Sore Muscle for Too Long

Heat feels good on sore muscles. That's why a soak in a hot tub or a steaming shower is such a relief. However, lengthy exposure to heat, especially heating pads, can do more harm than good. Even though heat therapy is a common part of physical therapy, you should avoid overusing a heating pad for sore muscles.

Heating pads can help reduce muscle soreness. Credit: JannHuizenga/iStock/GettyImages


Prolonged exposure to a heating pad may cause burns and increased inflammation. Play it safe by using a warm compress for heat therapy: Soak a clean washcloth or gauze in warm water, squeeze it semi-dry and apply it to the sore muscle for about 20 minutes.

What's Causing That Soreness?

Muscle soreness most often results from an overuse injury or from some sort of tension. Muscle overuse during exercise comes from microscopic injury to the muscle fibers. Those fibers become inflamed as part of your body's natural response to injury. You'll start to feel the pain within hours of an intense workout.

Muscle tension has two main sources: emotional stress and poor posture. Both of these types of tension can cause muscles to go into spasm, which leads to aching. Sore muscles from tension are similar to a small cramp and are the result of muscle fatigue.

Read more: 12 Simple Sitting Adjustments to Reduce Back Pain

Why Heat Therapy Helps

If soreness is the main symptom you're feeling, heat therapy can definitely come to the rescue. Heat helps sore muscles because when you apply heat to a muscle, it opens up the blood vessels in that area. This action increases blood flow.

That improved circulation creates both a short-term and long-term effect. The immediate effect is that the heating pad relaxes the muscles, which provides an immediate soothing sensation. In the longer term, heat therapy also accelerates some of your healing, because increased blood flow brings more cells that help repair the area faster.

Avoid Heating Pad Side Effects

Here's the potential problem with increasing blood flow: It also increases inflammation. If you have an acute injury, extra swelling is the last thing you need. Inflammation of your muscles is not just a symptom, but a cause, of muscle soreness. That's why anything you do that increases inflammation may slow your healing and cause additional pain once you take the heat off.

Reduce Burn Dangers

Although less common than other heating pad problems, burns are a danger if the heating pad is left on too long. It's possible to sustain first-, second- or even third-degree burns by leaving a heating pad on the same area for too long.

This is an especially serious risk for people with diabetes or other conditions that reduce sensitivity. It doesn't have to hurt while the heating pad is on for the danger to be there. Just as you can get a sunburn without feeling anything until it's too late, the long application of slightly too-warm heating pads can cook your skin.


Heating pads can pose a serious fire risk if basic safety precautions are ignored. Avoid sleeping with a heating pad on. In addition, make sure to check for frayed cords. Prevent the device from overheating by making sure no blankets, pillows or clothing covers the heating pad.

Use Common-Sense Precautions

Follow your doctor's instructions for whether to use cold or heat therapy following a muscle injury. A medical professional can also demonstrate the proper way to apply a heating pad for sore muscles. For any injury or soreness, you should always check with your medical professional before beginning or discontinuing a home treatment program.

Read more: How to Ease Muscle Soreness After a Workout

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.
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