Painful Muscles

Differential Diagnosis

Common Diagnoses

  • Overuse (Including Strain Injury)
  • Acute Viral Illness
  • Depression
  • Polymyalgia Rheumatica
  • Side Effects of Statins (Myalgia Much More Common than Myositis)

Occasional Diagnoses

  • Vitamin D Deficiency
  • Referred Joint Pain (e.g. from Hip to Thigh, Neck to Shoulder, Shoulder to Arm)
  • Fibromyalgia
  • Chronic fatigue syndrome
  • Connective Tissue Disease (e.g. RA, SLE, Polyarteritis Nodosa [PAN], Scleroderma)
  • Peripheral Vascular Disease: Intermittent Claudication
  • Neuropathy: Diabetic, Alcoholic
  • Bornholm Disease (Epidemic Myalgia, Devil’s Grip)
  • Drugs other than Statins: Clofibrate, Street Drug Withdrawal, Chemotherapy, Lithium, Cimetidine

Rare Diagnoses

Ready Reckoner

Key distinguishing features of the most common diagnoses

OveruseViral IllnessDepressionPMRStatin Side Effect
Sudden OnsetYesYesNoPossiblePossible
Morning StiffnessYesPossibleNoYesNo
Vague GeneralisedNoPossibleYesNoPossible
PersistentNoNoYesYesYes
Muscle TendernessYesPossibleNoPossiblePossible

Possible Investigations

Likely:FBC, ESR/CRP.

Possible:Urinalysis, autoimmune blood tests, TFT, LFT, blood sugar or HbA1c, creatine phosphokinase (CPK), vitamin D levels.

Small Print:Joint and chest X-rays, HIV test, Lyme disease serology; in secondary care, angiography, electromyography, muscle biopsy, lumbar puncture, urinary porphyrins.

  • Urinalysis: Glycosuria in undiagnosed diabetes Proteinuria and/or haematuria may be present in connective tissue disease.
  • FBC and ESR/CRP: Hb may be depressed in connective tissue disease and PMR. WCC and ESR/CRP raised in any inflammatory disorder (ESR more useful than CRP in PMR); MCV elevated in hypothyroidism and alcohol abuse.
  • Autoimmune blood tests: May be helpful if connective tissue disorder suspected.
  • TFT: Will confirm hypothyroidism.
  • Blood sugar or HbA1c, LFT: The former to confirm diabetes; the latter may help in confirming an alcohol problem. Both may cause a neuropathy resulting in muscle pain.
  • CPK: Raised in acute inflammatory and viral myopathies.
  • Vitamin D levels: Vitamin D deficiency is increasingly being recognised and may present with muscle pain and/or weakness.
  • HIV test or Lyme disease serology: For HIV infection or Lyme disease.
  • Joint X-rays: If referred pain from primary joint pathology suspected.
  • Angiography: For peripheral vascular disease.
  • Electromyography and muscle biopsy (both in secondary care): To confirm diagnosis of polymyositis or dermatomyositis.
  • Lumbar puncture: To examine CSF in hospital in suspected Guillain–Barré syndrome or poliomyelitis.
  • Urinary porphyrins: To exclude porphyria.
  • Other investigations for suspected underlying malignancy (e.g. CXR).

Top Tips

  • In polysymptomatic patients with muscle pain but no objective signs and normal blood tests, consider fibromyalgia, depression and chronic fatigue (Note: These problems may coexist).
  • The diagnosis of PMR is clinched by a trial of prednisolone (15 mg/day). In PMR, this treatment should lead to total resolution of symptoms within a few days.
  • Muscle pain is more likely to be associated with significant pathology in the very young and old than the middle-aged, when psychological causes and overuse are the most likely.

Red Flags

  • Always remember PMR in the older patient complaining of aching pain and stiffness in the hip and shoulder girdle muscles which is worse in the mornings.
  • If considering PMR, or initiating treatment in this condition, enquire after symptoms of temporal arteritis. About 30% of patients develop this complication, and are at risk of blindness.
  • Muscle pain with significant and progressive weakness (e.g. difficulty climbing stairs or getting out of a chair) suggests polymyositis, hypothyroidism, vitamin D deficiency or malignancy.
  • Significant underlying disease (e.g. PMR, polymyositis, dermatomyositis or connective tissue disease) is likely if there is an arthritis associated with the muscle pain.

Published: 2nd August 2022 Updated: 10th April 2024

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Nursing in Practice Reference is based on the best-selling book Symptom Sorter. The experts behind Nursing in Practice Reference are Marilyn Eveleigh who is Nursing in Practice’s editorial advisor and a primary care nurse in East Sussex, Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.