Thermotherapy is the use of heat to treat symptoms of acute or chronic pain, especially those related to muscle tension or spasm. It is also a common treatment for arthritis, bursitis, tendinitis, back pain, shoulder pain and other kinds of joint pain.

Thermotherapy widens blood vessels and increases blood flow to the skin. It relaxes superficial muscles, decreases muscle spasms and reduces stiffness of joints. Research has shown that it can also block pain receptors.

People often apply heat therapy at home for minor conditions. It is also used in healthcare settings, such as physical therapy, manipulation therapy and occupational therapy.

There are several methods of delivering thermotherapy to the body. They include:

• Warm compresses and hot packs
• Heating pads
• Heat creams and ointments
• Paraffin dips and whirlpool baths
• Ultrasound therapy
• Diathermy, a treatment using microwaves or shortwaves

Moist heat appears to be more effective in treating pain than dry heat, as the moisture allows the heat to penetrate more deeply into the muscle. Thermotherapy is frequently used combination with other therapies to relieve pain, such as hydrotherapy (water therapy). In many cases, cryotherapy (cold therapy) is used to reduce inflammation before thermotherapy is used to increase blood flow to muscles.

Thermotherapy is generally safe but does carry risks if improperly used and is not appropriate for some individuals and conditions. Patients should consult their physician before using thermotherapy.