Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Bulbar, respiratory, cardiac or rapidly progressive disease
Dysphagia with aspiration, weak cough, falling vital capacity, respiratory failure, myocarditis, arrhythmia or rapidly progressive ILD can deteriorate before limb weakness or CK appears severe.
Action: Admit urgently, assess airway and swallowing, measure respiratory function and ECG or troponin, investigate infection and ILD, and begin specialist high-dose treatment with early steroid-sparing therapy when active myositis is confirmed or strongly suspected.
Synopsis
Recognise inflammatory myopathy from objective weakness, characteristic skin and organ features, exclude common mimics and inclusion-body myositis, investigate dysphagia, lung and malignancy risk, and restore function with prompt steroid-sparing treatment.
Suspect inflammatory myopathy with subacute symmetrical proximal weakness affecting stairs, rising, lifting and hair care; distinguish inability from pain, fatigue and breathlessness.
Dermatomyositis signs include heliotrope oedema, Gottron papules or sign, shawl or V-sign erythema, periungual capillary change, scalp inflammation and mechanic hands.
True polymyositis is a diagnosis of exclusion; reconsider inclusion-body myositis, immune-mediated necrotising myopathy, antisynthetase disease, drug, endocrine and inherited causes before applying it.
Key red flags
Choking, wet voice, nasal regurgitation, recurrent pneumonia or inability to handle secretions requires urgent speech-and-language and respiratory assessment.
Bulbar weakness
Wet voice, coughing with meals, nasal regurgitation, weight loss and recurrent chest infection indicates dysphagia and aspiration risk.
Investigation priorities
01
CK, aldolase, AST, ALT, LDH and urinalysisFirst step
Quantify muscle injury, detect rhabdomyolysis complications and create a response baseline.
Management branches
First-line diagnostic sequenceProve weakness and define phenotype
Subacute proximal weakness, dermatomyositis rash or unexplained CK elevation raises inflammatory-myopathy suspicion.
Measure functional and manual strength, skin, joints, sensation, reflexes, swallowing, cough and respiratory symptoms and review statin, steroid, endocrine and family history.
Obtain enzymes, renal and urine, thyroid, inflammatory and phenotype-directed myositis antibodies, then MRI and EMG to select further testing.
Key medicines
PrednisoloneFor active adult inflammatory myopathy, start about 0.5–1 mg/kg orally once daily, commonly capped near 60 mg/day, then taper against strength, function, enzymes and organ response with early steroid-sparing therapy.
Intravenous methylprednisoloneFor severe bulbar, respiratory, cardiac or rapidly progressive disease, specialists commonly give 500–1,000 mg intravenously once daily for three days before a planned oral regimen.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.