Dermatomyositis is a rare autoimmune myopathy with characteristic cutaneous features, affecting roughly 1-10 new cases per million adults per year. It is defined by symmetric proximal muscle weakness developing over weeks to months alongside pathognomonic skin signs — heliotrope rash on the upper eyelids and Gottron papules over the knuckles, elbows, and knees.
Dermatomyositis (ICD-10: M33.1, M33.0 for juvenile) is an immune-mediated inflammatory myopathy characterised by symmetric proximal muscle weakness and pathognomonic skin findings. The pathology centres on a perifascicular atrophy pattern with complement-mediated capillary injury and a Type 1 interferon signature; the disease is now understood as a humoral and interferon-driven vasculopathy rather than a purely T-cell-mediated myositis. The 2017 EULAR/ACR classification criteria require characteristic skin findings (heliotrope, Gottron) or muscle weakness pattern, supported by elevated muscle enzymes (creatine kinase, aldolase), abnormal electromyography, MRI muscle oedema, and biopsy showing perifascicular atrophy. Myositis-specific autoantibodies define clinically meaningful subsets: anti-Mi-2 (classic skin and muscle, good response), anti-MDA5 (clinically amyopathic with rapidly progressive interstitial lung disease, especially in East Asians), anti-TIF1γ and anti-NXP2 (strong cancer association in adults), anti-SAE (rapid skin onset with subsequent muscle disease), and anti-synthetase antibodies including Jo-1 (interstitial lung disease, mechanic's hands, Raynaud).
key facts
Prevalence
Annual incidence 1-10 per million adults; prevalence approximately 10-20 per 100,000
Demographics
Female:male ratio approximately 2:1; juvenile form roughly equal sex distribution
Avg. age
Bimodal: peak 5-15 years (juvenile) and 40-60 years (adult)
Global cases
Estimated 200,000-300,000 people worldwide; cancer-associated dermatomyositis accounts for 15-25% of adult cases
Specialist
Rheumatology
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How you might notice it
The key symptoms of Dermatomyositis are: Symmetric proximal muscle weakness developing over weeks to months — difficulty rising from chairs, climbing stairs, lifting arms overhead, or washing hair., Heliotrope rash: violaceous discolouration of the upper eyelids with or without periorbital oedema, often the first cutaneous finding., Gottron papules: pink-purple papules over the dorsal metacarpophalangeal and interphalangeal joints; sometimes also elbows, knees, or medial malleoli., Photodistributed violaceous erythema on the upper chest (V-sign), upper back and shoulders (shawl sign), and lateral thighs (holster sign)., Periungual erythema, dilated capillaries on capillaroscopy, and ragged cuticles with painful infarcts., Mechanic's hands — fissured, hyperkeratotic, dry skin on the lateral fingers and palms — in the antisynthetase syndrome., Dysphagia with choking or nasal regurgitation from pharyngeal and upper oesophageal striated muscle involvement..
01Symmetric proximal muscle weakness developing over weeks to months — difficulty rising from chairs, climbing stairs, lifting arms overhead, or washing hair.
02Heliotrope rash: violaceous discolouration of the upper eyelids with or without periorbital oedema, often the first cutaneous finding.
03Gottron papules: pink-purple papules over the dorsal metacarpophalangeal and interphalangeal joints; sometimes also elbows, knees, or medial malleoli.
04Photodistributed violaceous erythema on the upper chest (V-sign), upper back and shoulders (shawl sign), and lateral thighs (holster sign).
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How it’s diagnosed
diagnosis
Diagnosis follows the 2017 EULAR/ACR classification criteria, which use a probability score based on age at onset, pattern of muscle weakness, cutaneous features, laboratory findings, and (where available) muscle biopsy. The minimum workup includes serum creatine kinase, aldolase, transaminases (often raised from muscle), lactate dehydrogenase, full blood count, urinalysis, antinuclear antibody, and myositis-specific antibody panel covering Mi-2, MDA5, TIF1γ, NXP2, SAE, and the synthetases (Jo-1 plus less common targets). Electromyography typically shows short-duration low-amplitude motor unit potentials with fibrillations and complex repetitive discharges; MRI of the thighs demonstrates muscle oedema (STIR hyperintensity) and atrophy and guides biopsy site. Muscle biopsy showing perifascicular atrophy, perivascular CD4 and B-cell infiltrates, MHC class I upregulation, and capillary depletion is highly supportive. High-resolution CT chest, pulmonary function tests with DLCO, and echocardiography assess interstitial lung disease and cardiac involvement. Video-fluoroscopic swallow study identifies pharyngeal and oesophageal dysphagia. All adults must undergo malignancy screening — chest, abdominal, and pelvic CT, mammography, gynaecological examination, faecal occult blood or colonoscopy if indicated by age, and tumour markers (CA-125 in women, PSA in men) — repeated annually for 3 years from diagnosis, given the 15-25% cancer association.
Key tests
01
Serum creatine kinase, aldolase, and transaminasesQuantifies muscle damage; elevations 5-50 times the upper limit of normal are typical of active myositis
02
Myositis-specific autoantibody panel (Mi-2, MDA5, TIF1γ, NXP2, SAE, Jo-1 and other synthetases)Defines clinical subset, predicts cancer risk, lung disease, and treatment response
03
Electromyography (EMG)
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Treatment & cost
medical treatments
✓Oral prednisolone 0.75-1 mg/kg/day (max 60-80 mg) tapered over months
✓Pulse intravenous methylprednisolone (500-1,000 mg daily for 3 days)
✓Methotrexate 15-25 mg weekly (oral or subcutaneous) plus folic acid
✓Mycophenolate mofetil 2-3 g/day in divided doses
surgical options
Surgical excision of large symptomatic calcinosis depositsSymptomatic improvement in 60-70% of patients; recurrence in adjacent sites 30-40%
Percutaneous endoscopic gastrostomy (PEG) feedingNutritional support adequate in over 90%; some patients reverse to oral intake as myositis improves
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Causes & risk factors
known causes
Autoimmune Type 1 interferon-driven vasculopathy
Upregulation of type I interferon (IFN-α/β) genes drives endothelial injury, complement deposition on capillaries, and perifascicular atrophy of muscle fibres. The interferon signature is now considered the unifying pathogenic feature.
Myositis-specific autoantibodies
Antibodies against intracellular antigens (Mi-2, MDA5, TIF1γ, NXP2, SAE, synthetases) define distinct clinical subsets and likely participate in pathogenesis. Each antibody is linked to a characteristic skin, muscle, lung, and cancer phenotype.
Underlying malignancy (paraneoplastic disease)
15-25% of adult cases have an underlying cancer diagnosed within 3 years of dermatomyositis onset. Strong association with anti-TIF1γ (risk roughly 50% in older adults) and anti-NXP2 antibodies. Tumour antigen-driven autoimmunity is the leading hypothesis.
Genetic susceptibility
HLA-DRB1*0301 (anti-Jo-1, anti-PM-Scl) and HLA-DRB1*0701 (anti-Mi-2) are well-established risk alleles. Genome-wide studies confirm multiple immune-regulatory loci.
Environmental and infectious triggers
Ultraviolet light exposure increases disease activity. Viral infections (coxsackie, parvovirus, HTLV-1, hepatitis C, SARS-CoV-2) have been implicated as triggers in case reports and cohort studies, particularly for juvenile disease.
Drug-induced dermatomyositis-like syndromes
Hydroxyurea, statins, anti-TNF agents, penicillamine, and immune checkpoint inhibitors (anti-PD-1 and anti-PD-L1) can produce dermatomyositis-like illness, sometimes overlapping with classic disease.
risk factors
Female sex
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Living with it
01Apply broad-spectrum SPF 50+ sunscreen daily and reapply during outdoor activity to limit cutaneous flares.
02Avoid midday sun exposure and use UV-protective clothing and wide-brimmed hats.
03Review all current medications for known dermatomyositis triggers (statins, hydroxyurea, checkpoint inhibitors) at diagnosis.
04Adhere strictly to immunosuppressive therapy to maintain remission and reduce calcinosis risk.
05Attend cancer screening at diagnosis and annually for 3 years.
06Vaccinate against influenza, pneumococcus, SARS-CoV-2, HPV, and shingles before high-dose immunosuppression.
recommended foods
•Mediterranean-style diet rich in fish, olive oil, vegetables, and fruits
•Adequate protein intake (1.2-1.6 g/kg/day) during muscle recovery
•Vitamin D and calcium supplementation to offset steroid-induced bone loss
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When to seek help
why see a rheumatology
Suspected dermatomyositis requires rheumatology referral for myositis-specific antibody testing, EMG, MRI, biopsy, and ILD workup. Anti-MDA5 patients with rapidly progressive lung disease should be managed jointly with respiratory medicine in a tertiary centre. Cancer screening should be coordinated with oncology and primary care. Juvenile cases need paediatric rheumatology with calcinosis and growth surveillance.
01Interstitial lung disease, especially anti-MDA5 rapidly progressive form — major cause of mortality; screen all patients with HRCT and pulmonary function tests.
02Associated malignancy in 15-25% of adult cases — repeat cancer screening annually for 3 years from diagnosis.
03Calcinosis cutis with chronic ulceration and infection, common in juvenile disease and refractory to most therapies.
04Severe dysphagia with aspiration pneumonia and weight loss.
05Cardiac involvement (myocarditis, conduction disease, heart failure) — screen with ECG and echocardiography at diagnosis and during flares.
Classic dermatomyositisProximal muscle weakness plus characteristic cutaneous features (heliotrope rash, Gottron papules). Most adult cases; responds to glucocorticoids plus methotrexate.
Clinically amyopathic dermatomyositis (CADM)Characteristic skin disease for at least 6 months without clinical or laboratory muscle involvement. Often anti-MDA5 antibody-positive; high risk of rapidly progressive interstitial lung disease.
Juvenile dermatomyositisOnset under age 16. Higher rates of calcinosis cutis and vasculopathy than adult disease; lower rates of associated cancer; better long-term prognosis with aggressive early treatment.
Cancer-associated dermatomyositisUnderlying malignancy diagnosed within 3 years of dermatomyositis onset, occurring in 15-25% of adult cases. Strong association with anti-TIF1γ and anti-NXP2 antibodies; ovarian, lung, breast, gastric, colorectal, pancreatic, and nasopharyngeal cancers (in East Asia) most common.
Antisynthetase syndromeDefined by anti-synthetase antibodies (anti-Jo-1 most common; also PL-7, PL-12, EJ, OJ, KS, Zo, Ha). Triad of myositis, interstitial lung disease, and arthritis with mechanic's hands and Raynaud phenomenon.
Overlap myositisDermatomyositis features with another systemic autoimmune disease (lupus, scleroderma, mixed connective tissue disease, rheumatoid arthritis). Treatment is tailored to the dominant disease and overlap features.
Living with Dermatomyositis
Timeline
Muscle enzymes typically fall within 4-8 weeks of induction. Strength recovery lags enzyme normalisation by 6-12 weeks. Cutaneous improvement is often slower than muscle improvement. Maximum response usually occurs by 6-12 months. Steroid tapering targets prednisolone 5-10 mg/day by 6-12 months. Long-term maintenance on methotrexate or mycophenolate is typical for 2-5 years.
Lifestyle
01Use SPF 50+ sunscreen and protective clothing every day.
02Adhere to immunosuppressive medications as prescribed; do not stop suddenly.
03Engage in supervised physical therapy and graded exercise to maintain strength.
04Maintain a balanced anti-inflammatory diet with adequate protein and calcium.
05Stop smoking and limit alcohol to under 14 units per week.
06Attend regular cancer screening visits during the first 3 years after diagnosis.
Daily management
01Take prescribed prednisolone, methotrexate, or mycophenolate at the same time each day.
02Apply broad-spectrum SPF 50+ sunscreen every morning and reapply during outdoor time.
Complementary approaches
Strict photoprotection and topical therapyDaily SPF 50+ broad-spectrum sunscreen, sun-protective clothing, and avoidance of midday sun. Topical tacrolimus 0.1% ointment or potent corticosteroids for localised facial and hand cutaneous disease.
Physical therapy and graded exercise programmeOnce muscle inflammation is controlled, progressive resistance and aerobic training improve strength and function. Early mobilisation during acute disease is also beneficial — bed rest worsens deconditioning.
Choosing a doctor
Choose a rheumatology centre with access to the full myositis antibody panel, muscle biopsy and pathology expertise, and a multidisciplinary ILD service. Ask about IVIG, rituximab, and JAK inhibitor availability. Confirm a structured cancer screening pathway for adult patients.
Patient support resources
The Myositis Association →US-based patient organisation for myositis (including dermatomyositis) with peer support, research updates, and disease information.
Myositis UK →UK patient charity offering helpline, regional groups, and patient information for myositis and dermatomyositis.
Dermatomyositis is a rare autoimmune disease causing inflammation of muscle and skin. Patients develop symmetric proximal muscle weakness, a violaceous rash on the eyelids (heliotrope), and Gottron papules over the knuckles, elbows, and knees. It can also affect the lungs, heart, and oesophagus.
What are the first signs of dermatomyositis?▾▴
Early signs include a violaceous discolouration of the upper eyelids, a photosensitive rash over the chest and shoulders, and progressive difficulty climbing stairs, rising from chairs, or lifting arms above the head. Skin signs often precede muscle symptoms by weeks to months.
Is dermatomyositis associated with cancer?▾▴
Yes. About 15-25% of adult cases have an underlying malignancy diagnosed within 3 years of dermatomyositis. Anti-TIF1-gamma antibody is the strongest predictor. Annual cancer screening (CT, mammography, gynaecological exam, colonoscopy, tumour markers) is recommended for 3 years after diagnosis.
First-line treatment is oral prednisolone 0.75-1 mg/kg/day combined with methotrexate or mycophenolate mofetil. Intravenous immunoglobulin is now widely used as a steroid-sparing agent based on the ProDERM trial. Rituximab and JAK inhibitors are reserved for refractory or severe disease.
Is dermatomyositis curable?▾▴
Dermatomyositis is not curable but can be brought into long remission with treatment. About 60-80% of adults achieve substantial improvement on combination immunosuppression. Most patients need long-term low-dose maintenance therapy. Cancer-associated cases often improve when the underlying tumour is treated.
What is anti-MDA5 dermatomyositis?▾▴
Anti-MDA5 dermatomyositis is a clinically amyopathic subtype with little muscle disease but a high risk of rapidly progressive interstitial lung disease, especially in East Asian patients. It carries 1-year mortality up to 40-60% without intensive triple therapy combining steroids, calcineurin inhibitors, and JAK inhibitors or rituximab.
What is the heliotrope rash?▾▴
Heliotrope rash is a violaceous (lilac-coloured) discolouration of the upper eyelids, sometimes with periorbital swelling. It is named after the colour of the heliotrope flower. It is pathognomonic for dermatomyositis when seen with proximal muscle weakness or Gottron papules.
What are Gottron papules?▾▴
Gottron papules are pink-purple, flat-topped papules over the dorsal metacarpophalangeal and interphalangeal joints, and sometimes elbows, knees, or medial malleoli. They are pathognomonic for dermatomyositis and often accompany the heliotrope rash and proximal muscle weakness.
Can children get dermatomyositis?▾▴
Yes. Juvenile dermatomyositis is the most common idiopathic inflammatory myopathy in childhood, with peak onset at age 5-15 years. Cancer association is much lower than in adults. Calcinosis cutis is more common but long-term outcomes are generally favourable with early aggressive treatment.
How does IVIG help dermatomyositis?▾▴
Intravenous immunoglobulin given as 2 g/kg every 4 weeks improves muscle strength, skin disease, and dysphagia. The ProDERM phase 3 trial (NEJM 2022) showed significant improvement in 79% of IVIG patients versus 44% on placebo at 16 weeks, with benefit sustained at 40 weeks.
Is sunlight a trigger for dermatomyositis?▾▴
Yes. Ultraviolet light exposure precipitates and worsens cutaneous disease. Patients should use SPF 50+ broad-spectrum sunscreen daily, UV-protective clothing, and avoid midday sun. Photoprotection often reduces the need for higher-dose immunosuppression.
Can dermatomyositis affect the lungs?▾▴
Yes. Interstitial lung disease affects 20-40% of adult dermatomyositis patients and is the main cause of mortality. Anti-MDA5 antibody predicts rapidly progressive ILD; anti-synthetase antibodies predict chronic ILD. High-resolution CT and pulmonary function tests are essential at diagnosis.
Is exercise safe with dermatomyositis?▾▴
Yes. Once acute inflammation is controlled, supervised aerobic and resistance exercise improves strength, function, and quality of life. Gentle range-of-motion exercises during the acute phase prevent contractures and deconditioning. Avoid sun exposure during outdoor exercise.
What is calcinosis cutis?▾▴
Calcinosis cutis is calcium deposition in skin, subcutaneous tissue, and sometimes muscle, leading to firm nodules, chronic ulcers, and secondary infection. It affects 30-70% of juvenile and 10-20% of adult cases. Treatments include diltiazem, bisphosphonates, sodium thiosulphate, and surgical excision for severe cases.
Are statins safe in dermatomyositis?▾▴
Statins can rarely trigger a dermatomyositis-like syndrome or worsen pre-existing disease. They should be reviewed at diagnosis and stopped if a temporal association is suspected. Hyperlipidaemia from steroid therapy may still need treatment with alternative agents.
Can dermatomyositis come back after remission?▾▴
Yes. Relapses occur in 30-50% of patients within 5 years, often when immunosuppression is reduced. Monitoring muscle enzymes, skin signs, and myositis-specific antibody titres detects relapse early. Restarting or escalating immunosuppression usually regains control.
What is the life expectancy with dermatomyositis?▾▴
Five-year survival in adult dermatomyositis without ILD or cancer is now 80-90%, and 95% in juvenile disease. Anti-MDA5 with rapidly progressive ILD and cancer-associated disease have substantially worse prognosis. Cardiovascular disease, infection, and malignancy are leading competing risks long-term.
Is dermatomyositis hereditary?▾▴
There is a genetic susceptibility component (HLA-DRB1*0301, HLA-DRB1*0701, and several immune-regulatory loci), but the disease is not directly inherited. Most cases are sporadic. Family members rarely develop dermatomyositis themselves but may have other autoimmune conditions.
Can I get pregnant with dermatomyositis?▾▴
Yes, when the disease is in remission for at least 6 months on pregnancy-safe medications (hydroxychloroquine, azathioprine, low-dose steroids, IVIG). Mycophenolate and methotrexate are teratogenic and must be stopped 3 months before conception. Multidisciplinary care improves outcomes.
How often should I have cancer screening?▾▴
All adults with new dermatomyositis should have age-appropriate cancer screening at diagnosis — chest, abdominal, and pelvic CT, mammography, gynaecological exam, colonoscopy if indicated, and tumour markers. Repeat screening every 6-12 months for at least 3 years, when cancer risk is highest.
Periungual erythema, dilated capillaries on capillaroscopy, and ragged cuticles with painful infarcts.
06Mechanic's hands — fissured, hyperkeratotic, dry skin on the lateral fingers and palms — in the antisynthetase syndrome.
07Dysphagia with choking or nasal regurgitation from pharyngeal and upper oesophageal striated muscle involvement.
08Dyspnoea on exertion, dry cough, and reduced exercise tolerance from interstitial lung disease, particularly in anti-MDA5 and antisynthetase patients.
09Polyarthralgia or non-erosive polyarthritis, usually small joints of the hands.
10Calcinosis cutis — subcutaneous and intramuscular calcium deposits, most common in juvenile dermatomyositis.
early warning signs
•Persistent violaceous discolouration of the upper eyelids without an obvious cause
•Photosensitive rash in a sun-exposed distribution (V-sign, shawl sign) developing over weeks
•Difficulty climbing stairs or rising from low chairs without using the hands
•Unexplained elevation of creatine kinase or transaminases on routine blood tests
•New cough, breathlessness, or fall in exercise tolerance in a patient with characteristic skin signs
● emergency signs
•Acute breathlessness, hypoxia, and bilateral pulmonary infiltrates — rapidly progressive interstitial lung disease, especially in anti-MDA5 patients
•Severe dysphagia with aspiration pneumonia, weight loss, and inability to swallow saliva
•Acute weakness affecting the diaphragm or respiratory muscles with falling vital capacity
•Severe gastrointestinal vasculopathy with abdominal pain, melena, or perforation (juvenile dermatomyositis)
•Newly identified malignancy presenting with weight loss, masses, or paraneoplastic features
Confirms inflammatory myopathic pattern with short-duration low-amplitude motor units, fibrillations, and complex repetitive discharges
04
MRI of thigh and proximal limb muscles (T2/STIR)Detects muscle oedema and fatty replacement; guides muscle biopsy site and monitors treatment response
05
Muscle biopsyDefinitive diagnosis through perifascicular atrophy, complement deposition, and capillary depletion
06
High-resolution CT chest and pulmonary function tests with DLCODetects interstitial lung disease, the major cause of mortality in dermatomyositis
07
Cancer screening (CT chest-abdomen-pelvis, mammography, gynaecological exam, age-appropriate colonoscopy, tumour markers)Detects underlying malignancy in 15-25% of adult patients; repeated annually for 3 years
Outlook
Outlook has improved substantially over the past three decades. With modern combination therapy, 5-year survival is now 80-90% in adult dermatomyositis without ILD or cancer, and 95% in juvenile disease. The main predictors of poor outcome are anti-MDA5 antibody with rapidly progressive interstitial lung disease (1-year mortality up to 40-60% in untreated East Asian cohorts), associated malignancy, severe dysphagia with aspiration, and cardiac involvement. Anti-TIF1γ-positive adult patients have the highest cancer risk (around 50% within 3 years). Sustained remission off all immunosuppression is achieved by a minority; most patients require long-term low-dose steroids or steroid-sparing therapy. Calcinosis develops in 30-70% of juvenile cases and 10-20% of adults and is difficult to reverse. Treatment of an associated cancer often substantially improves dermatomyositis; persistent disease after cancer therapy implies a separate non-paraneoplastic course.
non-modifiable
Approximately 2:1 female predominance in adults. Juvenile dermatomyositis is roughly equal between sexes.
Age 40-60 years (adult) or 5-15 years (juvenile)non-modifiable
Bimodal age distribution. Cancer risk rises sharply with adult onset, particularly above age 60.
HLA susceptibilitygenetic
HLA-DRB1*0301 and HLA-DRB1*0701 are associated with antisynthetase and anti-Mi-2 subsets respectively. Genetic risk is small in individual terms but informs the immunological framework.
Underlying malignancynon-modifiable
Cancer risk is highest in the first 3 years after dermatomyositis diagnosis (standardised incidence ratio 3-7) and particularly with anti-TIF1γ and anti-NXP2 antibodies.
East Asian ancestry (anti-MDA5)genetic
Anti-MDA5 antibodies and rapidly progressive interstitial lung disease are more common in East Asian patients (Japanese, Chinese, Korean cohorts) than in Western populations.
Cumulative ultraviolet light exposuremodifiable
UV light precipitates and worsens cutaneous disease and may have a role in inducing autoimmunity. Strict photoprotection is recommended.
Use of certain drugs (statins, hydroxyurea, checkpoint inhibitors)modifiable
Can induce dermatomyositis-like syndromes. Drug history is essential at diagnosis.
•Soft-texture foods and thickened liquids if pharyngeal dysphagia is present
foods to avoid
•Excess simple sugars and refined carbohydrates that worsen steroid-induced metabolic syndrome
•Heavy alcohol intake which exacerbates fatty liver and bone loss
•Raw or undercooked foods during high-dose immunosuppression (Listeria risk)
•Grapefruit and grapefruit juice while on tacrolimus or other calcineurin inhibitors
03Muscle biopsy and renal/muscle pathology service
04High-resolution CT chest and lung function testing
05Cancer screening pathway and oncology liaison
Essential facilities
Tertiary rheumatology centres with myositis subspecialty clinicsSpecialist ILD and pulmonary fibrosis servicesPaediatric rheumatology centresDay-case immunology infusion unitsOncology and gynaecology services for cancer screening
03
Attend infusion appointments for IVIG, rituximab, or cyclophosphamide as scheduled.
04Monitor for new rash, weakness, dysphagia, or breathlessness and report promptly.
05Perform prescribed physical therapy exercises twice daily during recovery.
06Attend regular blood tests for muscle enzymes, full blood count, liver and renal function.
Exercise
Begin gentle range-of-motion exercises and light isometric work during the acute inflammatory phase under physiotherapy guidance — bed rest worsens deconditioning. Once muscle enzymes normalise, progress to graded resistance training and aerobic exercise (3-5 sessions per week, 30-45 minutes). Severe weakness or interstitial lung disease may need pulmonary rehabilitation. Avoid sun exposure during outdoor exercise.