What Is Diathermy?

Medically Reviewed by Carmelita Swiner, MD on July 07, 2023
Written by WebMD Editorial Contributors
3 min read

Diathermy is a treatment option that uses energy sources to deep heat areas of your body. Rather than a heat source, diathermy uses sources like sound and electricity, which are converted into heat by your body. ‌

Diathermy, also called “deep heating,” heats deep below the surface of your skin. It targets muscles and joints to provide therapeutic benefits. 

There are three primary types of diathermy. Each method uses a different type of energy to produce deep heat. ‌

Radio wave Diathermy. Radio wave diathermy is also called high-frequency diathermy and shortwave diathermy. This treatment uses high-frequency electromagnetic currents transmitted deep into your tissue. ‌

Microwave Diathermy. This type of diathermy uses microwaves, a type of electromagnetic radiation. Microwave diathermy uses the same very high frequencies as a microwave oven!‌

Ultrasound diathermy. This method of diathermy is also called ultrasonic therapy. It uses high-frequency sound to create a gentle heat. 

Both types of diathermy produce deep heat in your body’s tissue. But they do it in unique ways with slightly different results. ‌

Any diathermy device should be able to maintain a temperature of 104 degrees Fahrenheit to 114 degrees Fahrenheit two inches below the skin. The ideal temperature should be reached in 20 minutes or less. ‌

How Radio Wave Diathermy Works. There are two primary methods for radio wave diathermy.

Dielectric coupled diathermy combines radio waves and an electric voltage. The radio wave diathermy device creates an electric field between electrodes positioned on either side of the body part. 

The electric charge travels through your tissue and disturbs the molecules. As the molecules attempt to realign themselves, they bump against each other and cause friction. Their friction leads to deep heat. ‌

Inductive coupled diathermy uses frequencies to generate a magnetic field. The device is positioned next to the body part, and the electromagnetic fields produce deep heat in your body’s tissues. ‌

How Microwave Diathermy Works. This type of diathermy applies microwave frequencies to the body part. The microwave radiation is transmitted into the tissue from an applicator. The size, shape, and distance of the applicator from the skin can all be adjusted for a specialized treatment. 

How Ultrasonic Diathermy Works. This method uses a tool with a round head and special gel. The gel is applied to the skin, and the tool (or “wand”) is rubbed across the area in a gentle circle. 

The wand sends ultrasonic energy through your tissue, creating deep heat below the surface. The gel helps the energy travel easier and provide therapeutic warmth. 

Most diathermy treatments relieve pain, tension, and inflammation in the muscles and joints. Each type of diathermy can be used to treat different conditions. ‌

Radio wave diathermy treatments. Radio wave diathermy effectively treats large-scale areas. It can be used to treat:

It can also be an effective treatment for various conditions, such as tendonitis, tenosynovitis, bursitis, arthritis, periostitis, and capsulitis. ‌

Microwave diathermy treatments. This method of diathermy is more selective. It targets specific muscles and applies deep heat to them. It can: 

  • Make your collagen tissue more flexible
  • Improve contractured muscles
  • Reduce muscle spasms
  • Treat joints in the hands, feet, and wrists

Ultrasound diathermy. This method is good for treating larger joints like the shoulder and hip. You can combine ultrasound therapy with physical therapy to improve your range of motion with your larger joints. ‌

Ultrasound diathermy can be used to treat a variety of conditions, including: 

The most common complication seen with diathermy is burning the patient. When the diathermy tool is left in the same place for too long without enough movement, the heat can build up and burn depending on the temperature of the treatment. ‌

However, burns typically occur from a combination of other factors, including compromised equipment, incorrect technique, and improper patient supervision. ‌

If you have metal implants, such as pins, dental fillings, or electrodes, you may be at risk when receiving radio wave diathermy. This is because the metal can become heated and put at risk for burns. ‌

Some conditions can increase your risk levels when using diathermy, including

  • You have a pacemaker or other implanted medical device
  • You have a malignant tumor in the treatment area
  • You have a fracture in the treatment area
  • You’re pregnant

If any of the above conditions apply to you, you should exercise caution and tell your doctor before proceeding with diathermy.