Because of limited clinical research, the causes of myofascial pain syndrome (MPS) are not thoroughly understood. However, physicians have identified several factors that can lead to the development of one or more trigger points (TrPs) resulting in chronic musculoskeletal pain. These include:

• Trauma to the musculoskeletal tissues (e.g., muscles, ligaments, tendons, bursae)
  
  
• Repetitive motion injuries, such as bursitis or tennis elbow

• Poor posture and ergonomics
  
  
• Skeletal asymmetry (e.g., gait disturbances such as leg-length discrepancies, short upper arms)
  
  
• Sedentary lifestyle
  
  
• Nervous tension or stress
  
  
• Clenching or grinding the teeth (bruxism)
  
  
• Sleep deprivation
  
  
• Nutritional deficiencies (e.g., low levels of calcium, potassium, iron and vitamins C, B1, B6 and B12)
  
  
• Hormonal changes, such as occurs during menstruation and menopause
  
  
• Chilling areas of the body (e.g., sitting under an air conditioning vent for long periods of time)
  
  
• Alcohol
  
  
• Smoking cigarettes
  
  
• Overexertion

Additionally, many chronic illnesses may activate TrPs, such as:

• Viral or bacterial infections
  
  
• Inflammatory diseases including:
  
  
• Rheumatoid arthritis. Inflammation of the joints that can lead to damage, pain and reduced movement.
  
  
• Fibromyalgia. A rheumatic condition characterized by widespread pain in the joints, muscles, tendons and other soft tissues, among other symptoms. MPS can also co-exist with fibromyalgia.
  
  
• Appendicitis, gallbladder or stomach inflammation.
  
  
• Lupus. An autoimmune disorder that can affect many systems, including the skin, joints and internal organs.
  
  
• Other conditions, such as abnormal levels of blood sugar (e.g., diabetes, hypoglycemia), heart attack, hyperuricemia (buildup of uric acid in the blood, associated with gout and kidney stones), and hypothyroidism (underactive thyroid gland).