The causes of polyarthralgia are diverse and can range from benign conditions to serious underlying diseases. It is often a symptom of an underlying condition rather than a disease itself. Common causes include:-

• Autoimmune and Inflammatory Conditions: These are a significant group of causes, even if inflammation is immediately apparent. Polyarthralgia can be an early sign.
  • Rheumatoid Arthritis (RA): A chronic inflammatory disorder primarily affecting the small joints of the hands and feet.
  • Systemic Lupus Erythematosus (SLE): A chronic autoimmune disease that can affect various organs and tissues, including joints.
  • Psoriatic Arthritis: A form of arthritis that affects some people with psoriasis.
  • Ankylosing Spondylitis and other Spondyloarthropathies: Inflammatory diseases primarily affecting the spine, but can also involve peripheral joints.
  • Polymyalgia Rheumatica: An inflammatory condition causing muscle pain and stiffness, predominantly in the shoulders and hips.
  • Vasculitis: Inflammation of blood vessels.
• Infections:-
  • Viral Infections: Many viral infections can cause temporary joint pain, including influenza, human parvovirus B19, hepatitis B and C, HIV, Chikungunya, and Rubella.
  • Bacterial Infections: Lyme disease, reactive arthritis (triggered by infections in the gut or urinary tract), septic arthritis (though usually monoarticular, can rarely be polyarticular), and post-streptococcal reactive arthritis (e.g., rheumatic fever).
• Degenerative Conditions:
  • Osteoarthritis (OA): While often affecting single joints or a few large joints, generalized osteoarthritis can lead to polyarthralgia. It is characterized by the breakdown of cartilage.
• Metabolic and Crystal-Induced Conditions:-
  • Gout: Caused by the build-up of uric acid crystals in joints, typically affects one joint at a time but can be polyarticular.
  • Pseudogout (Calcium Pyrophosphate Deposition Disease – CPPD): Caused by calcium pyrophosphate crystals.
• Other Musculoskeletal Conditions:
  • Fibromyalgia: A chronic disorder characterized by widespread musculoskeletal pain, fatigue, and other symptoms.
  • Hypermobility Syndromes: Conditions where joints move beyond the normal range, leading to pain.
  • Overuse or Trauma: Repetitive stress, strenuous exercise, or minor injuries can lead to pain in multiple joints.
  • Bursitis or Tendinitis: Inflammation of bursae or tendons around joints, which can cause pain that feels like it’s in the joint.
• Less Common Causes:-
• Cancers: Rarely, polyarthralgia can be a paraneoplastic symptom or due to direct involvement of joints.
• Medication Side Effects: Certain drugs can cause joint pain.
• Vitamin Deficiencies: Such as low vitamin D.
• Thyroid disorders.