Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

severe idiopathic inflammatory myopathies: initial presentation

1st line – induction therapy: intravenous corticosteroid

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ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
1st line – 

induction therapy: intravenous corticosteroid

For patients with severe forms of myositis defined as severe muscle weakness (e.g., global weakness with strength worse than 4 on Medical Research Council scale), respiratory failure from interstitial lung disease, myocarditis, severe dysphagia, or other life-threatening complications, an initial course of pulse dosing of intravenous corticosteroids (e.g., methylprednisolone) should be considered to allow for increased therapeutic effect and less toxicity compared with oral corticosteroids.​[4][72][93]​​ 

Following intravenous corticosteroid treatment, patients should be converted to a high-dose oral corticosteroid (e.g., prednisolone), which is then tapered over several months according to clinical response.[72]​​[93]

Corticosteroid regimens may vary; check your local guidelines for more information.

Primary options

methylprednisolone sodium succinate: 1 g intravenously every 24 hours for 3-5 days

and

prednisolone: 0.5 to 1 mg/kg/day orally initially following completion of intravenous methylprednisolone course, gradually taper according to response, maximum 80 mg/day

Plus – methotrexate or azathioprine or mycophenolate

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ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
Plus – 

methotrexate or azathioprine or mycophenolate

Treatment recommended for ALL patients in selected patient group

Immunosuppressants (used as corticosteroid-sparing agents) should be initiated early to reduce muscle inflammation, achieve clinical remission, and reduce corticosteroid burden.​[4][72][93]​​ Conventional synthetic disease-modifying antirheumatic drugs (DMARDs) such as methotrexate, azathioprine, and mycophenolate are recommended in addition to corticosteroid treatment. However, the British Society of Rheumatology guideline suggests that there is no evidence to determine which conventional synthetic DMARD should be first line. They state that DMARDs should be prescribed and monitored according to existing age appropriate guidelines.[93] Other evidence suggests that methotrexate or azathioprine should be first-line treatment.[4] 

Mycophenolate may be considered a first-line treatment for patients with severe idiopathic inflammatory myopathy (IIM) with associated interstitial lung disease (ILD).[4][94]​​ Retrospective and prospective studies have demonstrated the efficacy of mycophenolate for the treatment of patients with IIM, particularly for patients with IIM-associated ILD and refractory dermatomyositis rashes.

Potential adverse effects of methotrexate include leukopenia, elevated liver enzymes, interstitial pneumonitis, and pulmonary fibrosis. Folic acid supplementation is recommended. Potential adverse effects of azathioprine include leukopenia, liver damage, and a range of gastrointestinal symptoms.[72]

Primary options

methotrexate: 7.5 to 25 mg orally/subcutaneously/intramuscularly once weekly on the same day of each week

OR

azathioprine: 25-50 mg orally once daily initially, increase gradually according to response, maximum 2 mg/kg/day

Secondary options

mycophenolate mofetil: 500 mg orally once or twice daily initially, increase gradually according to response, maximum 3000 mg/day in 2 divided doses

Consider – intravenous immunoglobulin (IVIG)

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ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is recommended for the treatment of severe muscle inflammation concomitantly with other immunosuppressants. It may also be used as monotherapy in the settings of pregnancy, infection, or malignancy.​[4][93][95]​​​​ The efficacy of IVIG has been demonstrated as a rescue treatment in patients with interstitial lung disease relapse, or in combination with early use of an intravenous corticosteroid.[57][95][96][97][98]​​​​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

2nd line – induction therapy: ciclosporin or tacrolimus or mycophenolate + corticosteroid

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ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
2nd line – 

induction therapy: ciclosporin or tacrolimus or mycophenolate + corticosteroid

If treatment with a corticosteroid and a first-line immunosuppressant is not tolerated or is ineffective, alternative second-line immunosuppressant options should be considered. These may include ciclosporin, tacrolimus, or mycophenolate. Corticosteroids should be continued concomitantly and tapered gradually according to response.

Oral ciclosporin and tacrolimus are effective immunosuppressants that can be used either as a replacement for, or in combination with, other immunosuppressants in patients with refractory myositis with either muscle weakness or associated interstitial lung disease.​[4][72]​​ Nephrotoxicity, gastrointestinal symptoms, hypertension, and rarely reversible posterior encephalopathy syndrome are potential adverse effects.[72][99]​​ Regular monitoring of serum drug trough levels, full blood count, renal function, and liver function should be performed.[100][101]​​ 

Mycophenolate can also be considered as a second-line treatment for patients with severe IIM who are refractory or intolerant to first-line immunosuppressants.[4]

Primary options

ciclosporin: consult specialist for guidance on dose

OR

tacrolimus: consult specialist for guidance on dose

OR

mycophenolate mofetil: 500 mg orally once or twice daily initially, increase gradually according to response, maximum 3000 mg/day in 2 divided doses

Consider – intravenous immunoglobulin (IVIG)

Back
ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.​[4][93]​​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

3rd line – induction therapy: rituximab or cyclophosphamide + corticosteroid

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ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
3rd line – 

induction therapy: rituximab or cyclophosphamide + corticosteroid

Third-line treatments for patients with severe idiopathic inflammatory myopathy (IIM) may include cyclophosphamide or rituximab.​[4][93]​​ Escalation to third-line treatment should be considered for patients who are refractory to, or intolerant of, corticosteroids and other immunosuppressants.[72] Corticosteroids should be continued concomitantly and tapered gradually according to response.

Cyclophosphamide can be considered for patients with severe muscle weakness, and interstitial lung disease (ILD) or rapidly progressive ILD associated with IIM, as remission induction therapy.​[4][93]​​ It may be associated with a high risk of opportunistic infections and its potential for liver, bladder, and bone marrow toxicity should be noted.[100][102]

Rituximab (an anti-CD20 monoclonal antibody biological agent) should be considered for patients with refractory myositis, and may be particularly effective for patients with a positive myositis autoantibody profile, or with lower burden of disease damage.[93] One randomised trial of rituximab in patients refractory to corticosteroids and at least one other immunosuppressant reported that although the primary end point (time to clinical improvement between two trial arms) was not met, 83% of the study population did met the definition of improvement during the trial period.[103] One review that included this trial found that rituximab may be an effective treatment for refractory IIM patients, but patients with autoantibodies anti-Jo-1 (anti-histidyl-tRNA synthetase) and anti-Mi-2 are more likely to respond to rituximab.[104] Several open-label studies have reported safety and efficacy in patients with severe and refractory myositis. including the subset of anti-SRP positive immune-mediated necrotising myopathy patients.[105][106]​ Rituximab also may be an effective option in anti-MDA5 dermatomyositis with severe lung involvement.​[79][107]​ Adverse effects include infusion reactions, severe mucocutaneous reactions, hepatitis B reactivation, and progressive multifocal leukoencephalopathy.

Primary options

rituximab: consult specialist for guidance on dose

OR

cyclophosphamide: consult specialist for guidance on dose

Consider – intravenous immunoglobulin (IVIG)

Back
ACUTE
|
severe idiopathic inflammatory myopathies: initial presentation
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93] Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

non-severe idiopathic inflammatory myopathies: initial presentation

1st line – induction therapy: oral corticosteroid

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
1st line – 

induction therapy: oral corticosteroid

Non-severe idiopathic inflammatory myopathy (IIM) includes patients with mild to moderate muscle weakness without any life-threatening complications.

Oral corticosteroids are the recommended first-line treatment for patients with non severe IIM.[4][72][93][108]​​​ Corticosteroids should be tapered according to clinical response once a corticosteroid-sparing agent is started.[4][93]​ The aim is to either stop the oral corticosteroid or maintain a low maintenance dose.

Corticosteroid regimens may vary; check your local guidelines for more information.

Primary options

prednisolone: 0.5 to 1 mg/kg/day orally initially, gradually taper according to response, maximum 80 mg/day, usual maintenance dose <5 mg/day

Plus – methotrexate or azathioprine

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
Plus – 

methotrexate or azathioprine

Treatment recommended for ALL patients in selected patient group

In addition to an oral corticosteroid, a conventional synthetic disease-modifying antirheumatic drug (DMARD) such as methotrexate or azathioprine should be introduced early (as a corticosteroid-sparing agent) to reduce muscle inflammation and corticosteroid burden.[4][93]

The BSR states that there is insufficient evidence to determine which drug is preferred first line. However, subsequent evidence suggests that methotrexate or azathioprine should be considered first line.[4][93]

Potential adverse effects of methotrexate include leukopenia, elevated liver enzymes, interstitial pneumonitis, and pulmonary fibrosis. Folic acid supplementation is recommended. Potential adverse effects of azathioprine include leukopenia, liver damage, and a range of gastrointestinal symptoms.[72]

Primary options

methotrexate: 7.5 to 25 mg orally/subcutaneously/intramuscularly once weekly on the same day of each week

OR

azathioprine: 25-50 mg orally once daily initially, increase gradually according to response, maximum 2 mg/kg/day

Consider – intravenous immunoglobulin (IVIG)

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93]​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

2nd line – induction therapy: ciclosporin or tacrolimus or mycophenolate + corticosteroid

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
2nd line – 

induction therapy: ciclosporin or tacrolimus or mycophenolate + corticosteroid

Treatment for patients with non-severe idiopathic inflammatory myopathy who are refractory or intolerant to first-line immunosuppression may include ciclosporin, tacrolimus, or mycophenolate.[4] Corticosteroids should be continued concomitantly and tapered gradually according to response.

Nephrotoxicity, gastrointestinal symptoms, hypertension, and rarely reversible posterior encephalopathy syndrome are potential adverse effects with ciclosporin and tacrolimus.[72][99] Regular monitoring of serum drug trough levels, full blood count, renal function, and liver function should be performed.[100][101]

Primary options

ciclosporin: consult specialist for guidance on dose

OR

tacrolimus: consult specialist for guidance on dose

OR

mycophenolate mofetil: 500 mg orally once or twice daily initially, increase gradually according to response, maximum 3000 mg/day in 2 divided doses

Consider – intravenous immunoglobulin (IVIG)

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93]​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

3rd line – induction therapy: rituximab or cyclophosphamide or abatacept + corticosteroid

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
3rd line – 

induction therapy: rituximab or cyclophosphamide or abatacept + corticosteroid

Rituximab, cyclophosphamide, or abatacept can be considered third-line treatment in patients with persistent active disease.​[93] Corticosteroids should be continued concomitantly and tapered gradually according to response.

Rituximab may be particularly effective for patients with a positive myositis autoantibody profile or with lower burden of disease damage.​[93] One randomised trial of rituximab in patients refractory to corticosteroids and at least one other immunotherapy agent reported that although the primary end point (time to clinical improvement between two trial arms) was not met, 83% of the study population did met the definition of improvement during the trial period.[103] One review that included this trial found that rituximab may be an effective treatment for refractory IIM patients, but patients with autoantibodies anti-Jo-1 (anti-histidyl-tRNA synthetase) and anti-Mi-2 are more likely to respond to rituximab.[104] Several open-label studies have reported safety and efficacy in patients with severe and refractory myositis. including the subset of anti-SRP positive immune-mediated necrotising myopathy patients.[105][106]​ Rituximab also may be an effective option in anti-MDA5 dermatomyositis with severe lung involvement.​[79][107]​ Adverse effects include infusion reactions, severe mucocutaneous reactions, hepatitis B reactivation, and progressive multifocal leukoencephalopathy.

Cyclophosphamide can be considered for patients with refractory disease as remission induction therapy.[4][93] It may be associated with a high risk of opportunistic infections and its potential for liver, bladder, and bone marrow toxicity should be noted.[100][102]

Abatacept, a fully human recombinant fusion protein that blocks T-cell activation, has been demonstrated to reduce disease activity in patients with dermatomyositis or polymyositis in a phase 2b randomised study.[109]

Primary options

rituximab: consult specialist for guidance on dose

OR

cyclophosphamide: consult specialist for guidance on dose

OR

abatacept: consult specialist for guidance on dose

Consider – intravenous immunoglobulin (IVIG)

Back
ACUTE
|
non-severe idiopathic inflammatory myopathies: initial presentation
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93]​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

ONGOING

remission achieved: any severity

1st line – maintenance therapy: immunosuppressant

Back
ONGOING
|
remission achieved: any severity
1st line – 

maintenance therapy: immunosuppressant

Immunosuppressants should be used to maintain idiopathic inflammatory myopathy remission and allow the dose reduction or withdrawal of corticosteroid treatment.[77]​ Corticosteroids should be continued concomitantly and tapered gradually according to response. The aim is to either stop the oral corticosteroid or maintain a low maintenance dose.

Methotrexate, azathioprine, and mycophenolate are effective maintenance treatments for most patients.[77] Mycophenolate, tacrolimus, or ciclosporin should be considered where interstitial lung disease is a predominant feature.[4]

Potential adverse effects of methotrexate include leukopenia, elevated liver enzymes, interstitial pneumonitis, and pulmonary fibrosis. Folic acid supplementation is recommended. Potential adverse effects of azathioprine include leukopenia, liver damage, and a range of gastrointestinal symptoms.[99]

Nephrotoxicity, gastrointestinal symptoms, hypertension, and rarely reversible posterior encephalopathy syndrome are potential adverse effects with ciclosporin and tacrolimus.[72][99] Regular monitoring of serum drug trough levels, full blood count, renal function, and liver function should be performed.[100][101]

Primary options

methotrexate: 7.5 to 25 mg orally/subcutaneously/intramuscularly once weekly on the same day of each week

OR

azathioprine: 25-50 mg orally once daily initially, increase gradually according to response, maximum 2 mg/kg/day

OR

mycophenolate mofetil: 500 mg orally once or twice daily initially, increase gradually according to response, maximum 3000 mg/day in 2 divided doses

Secondary options

ciclosporin: consult specialist for guidance on dose

OR

tacrolimus: consult specialist for guidance on dose

Consider – intravenous immunoglobulin (IVIG)

Back
ONGOING
|
remission achieved: any severity
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93]​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

2nd line – maintenance therapy: immunosuppressant combination therapy

Back
ONGOING
|
remission achieved: any severity
2nd line – 

maintenance therapy: immunosuppressant combination therapy

For refractory patients, treatment escalation to combination therapy with ciclosporin plus methotrexate, or methotrexate or azathioprine plus mycophenolate, can be considered.[77] Consult a specialist for guidance on suitable combination regimens.

Consider – intravenous immunoglobulin (IVIG)

Back
ONGOING
|
remission achieved: any severity
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93]​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

3rd line – maintenance therapy: alternative immunosuppressant

Back
ONGOING
|
remission achieved: any severity
3rd line – 

maintenance therapy: alternative immunosuppressant

For patients with more resistant disease, treatment with tacrolimus (if not used as first-line treatment for patients with predominant interstitial lung disease), cyclophosphamide, rituximab, tocilizumab or abatacept can also be considered under specialist care for more resistant cases.[77]

Primary options

tacrolimus: consult specialist for guidance on dose

OR

rituximab: consult specialist for guidance on dose

OR

cyclophosphamide: consult specialist for guidance on dose

OR

tocilizumab: consult specialist for guidance on dose

OR

abatacept: consult specialist for guidance on dose

Consider – intravenous immunoglobulin (IVIG)

Back
ONGOING
|
remission achieved: any severity
Consider – 

intravenous immunoglobulin (IVIG)

Additional treatment recommended for SOME patients in selected patient group

IVIG is a well-established alternative corticosteroid-sparing agent or adjunct treatment for patients with severe or refractory idiopathic inflammatory myopathy and should be considered in combination with, or following failure of, corticosteroids and/or other immunosuppressants.[4][93]​​​ Adverse effects include renal toxicity and thrombosis.

Primary options

normal immunoglobulin human: 2 g/kg intravenously (administered in divided doses over 2-5 consecutive days) every 4 weeks

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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