woman uses a cold compress on her neck

When it comes to treating minor injuries or discomfort, hot and cold therapy are a common source of relief. These seemingly opposite options can banish inflammation from a sore muscle, reduce the pain around a joint, and expedite recovery — all without the use of medication. The natural benefits of hot and cold therapy are why many people turn to these solutions for assistance with everything from arthritic pain, to repetitive wrist strain.

Though heat and cold address pain in different ways, the ultimate benefit is the same — relief from ongoing discomfort. As a rule of thumb, ice is for acute pain, injuries, and inflammation, while heat is best applied to muscle stiffness and discomfort. Here, we'll look at the basics of heat and cold therapy, and when you should be using them.

What is Heat Therapy and How Does It Work?

Heat is effective at reducing pain because it causes blood vessels to expand, or dilate. As more blood flows to the area and nourishes damaged tissues with oxygen and minerals, we experience an instant soothing effect. Heat therapy can also reduce stiffness by making muscle tissue more supple and flexible.

Heat works for chronic pain, muscle discomfort, and stress. It soothes the body by minimizing tension and can also have a comforting effect on the mind, which is reassuring when we're feeling overwhelmed or nervous. Apply heat to:

  • Cramping or spasm-based pain
  • Aching pains from chronic conditions
  • Tight or painful muscles

When Not to Use Heat Therapy

Heat therapy isn't appropriate for inflamed or bruised skin. Additionally, never use heat therapy on a brand new injury; its ability to speed up circulation can increase bleeding beneath the skin and make the issue worse. The exception to the rule is acute back strains. Because back pain is due to muscle spasm rather than tissue damage, heat can be helpful.

People who suffer from pre-existing conditions that might respond poorly to heat therapy should speak to their doctor before self-medicating. For instance, show caution if you have vascular disease, diabetes, or multiple sclerosis.

What is Cold Therapy and How Does It Work?

Cold therapy, or "cryotherapy," performs the opposite function to heat by limiting blood flow in a specific area. This reduces the sensitivity of nerve endings, and can instantly reduce pain. Additionally, lower circulation means less swelling, which reduces the amount of pressure on a joint, muscle, or tendon.

Cold packs or ice are often intended for acute injuries like muscle tears, sprained ankles, inflammation, and bruising. Cold therapy helps to reduce the symptoms of sudden injury by:

  • Constricting the blood vessels and reducing the amount of fluid that gathers around an injury, limiting swelling or bruising
  • Numbing the nerve endings, which restricts the number of pain messages sent to the brain
  • Cooling the heat associated with "hot" injuries like cuts, bruises, or burns

When Not to Use Cold Therapy

Like with heat therapy, it's important to be cautious using cold therapy. Make sure that you never apply ice directly to the skin, as this can cause tissue damage. Instead, wrap ice or frozen produce in a towel or cloth first.

Avoid using cold therapy if you have sensory problems that might impair your ability to feel specific sensations. This includes people with diabetes who can have reduced sensitivity. Additionally, speak to your doctor before using cryotherapy if you have heart disease or cardiovascular issues.

Using Combined Heat and Cold Therapy

In some cases, it can be beneficial to use a combination of heat and cold therapy. While it's typically a good idea to start with cold therapy for acute injuries, after the swelling has begun to recede, you can alternate hot and cold treatment for an effective level of recovery and pain relief. This is perfect for people with overuse injuries, muscle tears, and chronic pain.

With alternating hot and cold therapy, the expansion in the blood cells from the heat and the contraction from the cold therapy behaves like a pump. During heat therapy, your blood vessels will expand and increase the flow of healing nutrients and oxygen. On the other hand, with cold therapy, the blood vessels will constrict, reducing the circulation and allowing the injured area more time to soak up the fresh blood.