Thermotherapy can be used to treat a number of pain conditions. These include:

• Muscle spasm. Persistent and often painful tension and shortness in a muscle or group of muscles that cannot be released voluntarily.
  
  
• Arthritis. Inflammation of a joint. Types of arthritis that may benefit from thermotherapy include:
  
  
• • Osteoarthritis
  • Rheumatoid arthritis
  • Juvenile arthritis
  • Juvenile rheumatoid arthritis
  • Ankylosing spondylitis
  • Gout
  • Psoriatic arthritis
  • Reiter’s syndrome
    
    
• Sources of back pain, such as a herniated disc. A frequently painful condition in which the cartilage (the tough, elastic, fibrous connective tissue) of an intervertebral disc (discs that serve as cushions between the vertebrae) bulges through its protective covering and presses on a nerve. Most of the time a herniated disc is associated with overlying muscle spasm, which heat therapy decreases.

Other conditions that may be treated with heat include back strain or sprain, degenerative disc disease, sciatica and scoliosis, as these conditions are usually associated with muscle spasm.

• Whiplash and other musculoskeletal types of neck pain.
  
  
• Shoulder pain, such as rotator cuff injuries. The rotator cuff is made up of the muscles and tendons that connect the humerus to the shoulder blade. Tendons in the rotator cuff are normally strong, but they can become inflamed and tear as a result of overuse, wear and tear associated with aging or an accident such as a collision. Another condition that may be eased by application of heat is a frozen shoulder.
  
  
• Other types of joint pain, including many forms of:
  
  
• • Arm pain (e.g., tennis elbow)
  • Leg pain (e.g., restless leg syndrome)
  • Knee pain (e.g., injured anterior cruciate ligament)
  • Foot pain (e.g., plantar fasciitis)

• Tendinitis. Inflammation of a tendon, a fibrous tissue connecting a muscle with its bony attachment.
  

• Bursitis. Inflammation of a bursa, a sac located between a tendon and a bone.
  
  
• Sprain. A painful wrenching or laceration of the ligaments of a joint.
  
  
• Eye pain. An ophthalmologist or other clinician may suggest applying warm compresses to relieve minor conditions such as blepharitis (inflammation of the eyelids).
  
  
• TMJ disorder. Applications of heat may help tender areas.
  
  
• Chest pain. Heat can supply relief from disorders such as costochondritis.
  
  
• Abdominal pain and pelvic pain. Researchers have found that externally applied heat such as hot-water bottles can relieve even deep internal pain for up to an hour by blocking pain receptors.
  
  
• Fibromyalgia. Therapeutic use of heat may help treat this chronic pain condition, characterized by musculoskeletal aches, pain and stiffness, tenderness in soft tissues, general fatigue and sleep disturbances.
  
  
• Other chronic pain disorders, including lupus and myofascial pain syndrome
  
  
• Asthma (see Types and differences)

Heat can also be used as a minimally invasive alternative to surgery. For example, several treatments for benign prostatic hyperplasia use microwaves, lasers or other sources of heat to destroy excess prostate tissue. High-intensity heat is also used to destroy some types of benign and cancerous tumors.

In addition, thermotherapy is used to reduce spasticity in neurological conditions. Recent studies indicate that a combination of thermotherapy and cryotherapy may help stroke patients recover arm function and may ease symptoms in people with heart failure. And other recent research suggests that a microwave form of thermotherapy might benefit women with advanced cervical cancer.