What are the common etiologies of generalized myalgia?

Generalized Myalgia: Common Etiologies

Generalized body aches (myalgia) most commonly arise from musculoskeletal conditions, viral infections, medication effects, systemic inflammatory disorders, and central pain syndromes—with musculoskeletal causes accounting for the majority of cases in primary care settings. 1

Primary Etiologic Categories

Musculoskeletal Causes (Most Common)

• Osteoarthritis and nonspecific musculoskeletal pain represent the most frequent etiologies, particularly affecting the back, neck, and large joints 1
• Low back pain is the single most common type of chronic pain, followed by arthritis 1
• Costochondritis and chest wall syndromes can present as localized or referred body aches 1
• Muscle strain, overuse injuries, and myofascial pain syndromes are common precipitants 1

Infectious Etiologies

• Viral myositis, particularly enterovirus epidemic myalgia (Bornholm disease/pleurodynia), causes acute generalized muscle pain 1
• Influenza and other systemic viral infections commonly produce diffuse myalgias 1
• Post-infectious persistent symptoms can occur following various viral illnesses 2

Medication-Related Causes

• Opioid-induced hyperalgesia paradoxically worsens pain with chronic opioid use 1
• Statin-induced myopathy should be considered in patients on lipid-lowering therapy 1
• Antiretroviral medications (particularly older agents like stavudine, didanosine) can cause myalgias through mitochondrial toxicity 1

Systemic Inflammatory and Rheumatologic Conditions

• Polymyalgia rheumatica presents with proximal muscle pain and stiffness, particularly in older adults 1
• Giant cell arteritis may manifest with systemic symptoms including myalgias 1
• Inflammatory arthritides (rheumatoid arthritis, spondyloarthritis) frequently cause widespread musculoskeletal pain 1
• Systemic lupus erythematosus and other connective tissue diseases produce diffuse myalgias 1

Central Pain Syndromes

• Fibromyalgia affects approximately 4% of women and 1% of men, characterized by widespread pain with multiple tender points and central sensitization 1
• Chronic widespread pain without meeting fibromyalgia criteria affects a larger population (approximately 11-15% of adults report chronic pain) 1
• These conditions involve altered central nervous system pain processing rather than peripheral tissue damage 1, 3

Neuropathic Pain

• HIV-associated neuropathy can present with generalized pain and discomfort 1
• Diabetic neuropathy, vitamin B12 deficiency, and thyroid dysfunction cause diffuse pain 1
• Post-herpetic neuralgia following varicella zoster infection produces regional pain 1

Metabolic and Endocrine Disorders

• Hypothyroidism commonly causes myalgias and should be excluded in patients with persistent body aches 4
• Vitamin D deficiency is associated with musculoskeletal pain 1
• Electrolyte disturbances can precipitate muscle pain 1

Critical Diagnostic Considerations

Red Flags Requiring Urgent Evaluation

• Fever, unintentional weight loss, or night sweats suggest infection, malignancy, or inflammatory disease 5
• Neurological symptoms (weakness, sensory changes, bowel/bladder dysfunction) mandate immediate assessment 5
• Constant pain, night pain, or symptoms lasting ≥4 weeks without improvement require investigation 5
• Visual symptoms or jaw claudication raise concern for giant cell arteritis 1

Distinguishing Features by Etiology

• Morning stiffness >30 minutes suggests inflammatory conditions rather than mechanical pain 1, 5
• Widespread pain disproportionate to objective findings with normal inflammatory markers points toward fibromyalgia or central pain syndromes 4, 3
• Pain with specific activity patterns (worse with use, better with rest) indicates mechanical/degenerative causes 1
• Tender points in characteristic locations support fibromyalgia diagnosis 4, 3

Laboratory and Imaging Approach

• Normal muscle enzymes (CK) generally differentiate fibromyalgia from inflammatory myopathies 4
• Inflammatory markers (ESR, CRP) help distinguish inflammatory from non-inflammatory causes, though IL-6 blockers can suppress these markers 1
• Imaging is not indicated for uncomplicated musculoskeletal pain without red flags 6
• MRI with contrast is appropriate when infection, malignancy, or inflammatory disease is suspected 5

Common Pitfalls to Avoid

Do not dismiss persistent symptoms as purely psychological—approximately 36% of primary care presentations involve symptoms without specific diagnosis, but these require systematic evaluation 7. The presence of central pain mechanisms (fibromyalgia) does not exclude coexisting inflammatory or structural disease requiring treatment 4.

Avoid premature opioid prescribing—opioids show limited long-term efficacy for chronic non-cancer pain and carry significant risks of dependence and paradoxical hyperalgesia 1. When musculoskeletal causes are identified, topical NSAIDs are preferred over systemic agents due to superior safety 6.

Recognize overlapping syndromes—many patients have features of multiple conditions (e.g., osteoarthritis with coexisting fibromyalgia), and composite disease activity scores may overestimate inflammatory activity when central pain is present 4, 2. Normal inflammatory markers do not exclude active inflammatory disease in patients on immunosuppressive therapy 1.

Consider medication effects systematically—review all medications for myalgia as a potential adverse effect, particularly statins, antiretrovirals, and chronic opioids 1.