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Autoimmune & autoinflammatory

Myositis overview

The idiopathic inflammatory myopathies - dermatomyositis, polymyositis, inclusion body myositis, necrotising myopathy and antisynthetase syndrome - all inflame muscle, but differ profoundly in course and treatment.

Key points

The essentials at a glance.

What to look out for, which tests matter, who treats it, and what usually happens next.

  • Hallmark: progressive weakness, classically of shoulders and hips - stairs, chairs and hair-washing become hard

  • Creatine kinase (CK) blood testing, myositis-specific antibodies, MRI and EMG build the case; biopsy remains the anchor in unclear cases

  • Myositis antibody panels now define subtypes with distinct risks - lung disease, cancer association, treatment response

  • Dermatomyositis adds characteristic rashes; inclusion body myositis follows a slower, treatment-resistant course

  • Screening for interstitial lung disease and age-appropriate cancer is part of the initial work-up, not an optional extra

Understanding it

About Myositis overview.

Muscle inflammation announces itself functionally: rising from a chair on the arms, climbing stairs one at a time, arms tiring above shoulder height. CK is usually elevated, but the modern revolution is antibody-driven - a panel of myositis-specific antibodies now sorts patients into syndromes with distinct fingerprints, from the Jo-1-positive antisynthetase patient whose lungs matter as much as muscles, to the TIF1-gamma-positive dermatomyositis patient whose work-up must chase malignancy, to the HMGCR-positive necrotising myopathy sometimes triggered by statins.

Diagnosis blends enzymes, antibodies, MRI-targeted biopsy and electromyography, and the treatment gap between subtypes is stark: most inflammatory myopathies respond to steroids and steroid-sparing agents, while inclusion body myositis largely does not, making accurate subtyping the single most consequential step. Early involvement of a clinician who manages myositis regularly - rheumatologist or neurologist - shortens the road considerably. In many parts of the UK, a routine NHS referral to the relevant specialist clinic currently means waiting many months - sometimes more than a year for the rarest conditions - whereas an initial appointment with a private consultant is typically available within around two weeks, with investigations arranged soon after.

Frequently asked

Common questions about Myositis overview.

Quick, plain-English answers to what people ask us most.

  • What is myositis?

    Myositis refers to a group of autoimmune conditions causing inflammation of the muscles, leading to progressive muscle weakness, and sometimes affecting the skin, lungs or other organs depending on the specific subtype.

  • What causes myositis?

    Myositis results from the immune system mistakenly attacking muscle tissue, with specific subtypes including dermatomyositis, polymyositis and inclusion body myositis, each having somewhat different triggers and associated antibodies.

  • What are the symptoms of myositis?

    Common symptoms include progressive muscle weakness, particularly affecting the hips, thighs, shoulders and upper arms, muscle pain or tenderness, fatigue, and in dermatomyositis, characteristic skin rashes.

  • Is myositis dangerous?

    It can be serious if it affects the muscles used for swallowing or breathing, or if associated with lung inflammation or, in some subtypes, an underlying cancer, which is why thorough assessment at diagnosis is important.

  • Can myositis be cured?

    Most forms of myositis cannot be cured outright but respond well to immunosuppressive treatment, achieving good symptom control, though inclusion body myositis tends to be more resistant to treatment and progresses more slowly regardless.

  • How is myositis treated?

    Treatment typically involves corticosteroids initially, followed by other immunosuppressive medications to control inflammation and reduce steroid use long term, alongside physiotherapy to maintain muscle strength and function.

  • When should I see a rheumatologist about suspected myositis, and how quickly can I be seen privately?

    See a rheumatologist promptly for unexplained progressive muscle weakness, particularly with skin changes or difficulty with stairs or standing from a chair. A private rheumatologist can typically arrange assessment and testing within about two weeks.