In short
Inflammatory myositis is a group of rare autoimmune conditions in which the immune system attacks the muscles, causing weakness in the hips, shoulders and neck. Dermatomyositis also causes a typical skin rash. Many people respond well to treatment, especially when it starts early.
On this page
What is myositis?
Myositis means muscle inflammation. The main forms are polymyositis (muscles only), dermatomyositis (muscles plus a skin rash) and inclusion body myositis, which progresses more slowly and is harder to treat.
It is most common in adults in their 40s and 50s, and affects women about twice as often as men.
What are the symptoms of myositis?
- Muscle weakness Hips, shoulders and neck — stairs, chairs and lifting get hard.
- Skin rash Purplish around the eyes, red bumps over the knuckles (dermatomyositis).
- Fatigue and aches Tiredness and sore muscles.
- Trouble swallowing Eating and drinking become harder.
- Breathlessness If breathing muscles or the lungs are involved.
- Joint pain Alongside the muscle symptoms.
How is myositis diagnosed?
- Blood tests Raised GlossaryCreatine Kinase (CK)An enzyme released by damaged muscle. Raised levels help diagnose and monitor myositis.All terms A–Z shows muscle damage; antibodies such as anti-Jo-1 identify the type.
- GlossaryEMG (Electromyography)A test of the muscles' electrical activity that shows whether weakness comes from the muscle or the nerve.All terms A–Z Measures muscle electrical activity to rule out nerve causes.
- MRI Shows exactly where muscles are inflamed.
- Muscle biopsy Confirms inflammation under the microscope.
- Lung tests If lung involvement is suspected.
How is myositis treated?
- Steroids Usually first, to bring inflammation down, then tapered.
- Immune-suppressing medicines Methotrexate or azathioprine for lasting control.
- Biologics Such as rituximab when standard treatment is not enough.
- Physiotherapy Rebuilds strength safely once inflammation settles.
- Supportive care Swallowing therapy, and sun protection for the rash.
What is the outlook?
- Many people with polymyositis or dermatomyositis return to a normal or near-normal routine.
- Many people reach remission with treatment; relapses can happen, so keep up follow-up.
- Pace your day, and tell people that weakness isn't always visible.
Questions patients ask
Is myositis contagious or hereditary?
It is not contagious. It is not directly inherited either — most people with myositis have no family history of it.
Can I exercise with myositis?
Yes — once inflammation is under control, guided exercise is encouraged. What is safe depends on how active your disease is, so follow the phased exercise programme with your physiotherapist.
What do antibody results like anti-Jo-1 mean?
Different antibodies go with different patterns: anti-Mi-2 often with classic dermatomyositis, anti-Jo-1 with lung and joint involvement, and anti-SRP with more severe muscle disease. Your rheumatologist will explain your own result.
Why does sun protection matter?
Sunlight can trigger or worsen the dermatomyositis rash, so use sunscreen and cover up.
Words worth knowing
Full glossary- Creatine Kinase (CK)
- An enzyme released by damaged muscle. Raised levels help diagnose and monitor myositis.
- EMG (Electromyography)
- A test of the muscles' electrical activity that shows whether weakness comes from the muscle or the nerve.
- Gottron's papules
- Red or purple bumps over the knuckles, elbows or knees, typical of dermatomyositis.
- Heliotrope rash
- A purplish rash around the eyes, typical of dermatomyositis.
- Interstitial lung disease
- Scarring or inflammation of the lungs that sometimes accompanies myositis and is monitored closely.
This page is intended for general patient education and does not replace personalized medical advice. Please consult your rheumatologist about your specific symptoms, diagnosis, or treatment plan. Last updated 3 October 2026.
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