1 What Is Polymyositis?

Polymyositis is an uncommon inflammatory disease that causes muscle weakness affecting both sides of the body. Polymyositis makes it difficult to walk or climb stairs, stand up from a seated position, and reach overhead or lift objects. In polymyositis, the white blood cells, the immune cells, of inflammation spontaneously invade muscles. Typically, the muscles closest to the trunk or torso are affected, which results in severe weakness. Polymyositis is characterized by progressive muscle weakness with periods of increased symptoms called “relapses” or “flares”. When there are no or minimal symptoms, it is known as “remissions”. If polymyositis is associated with a characteristic skin rash, it is called “dermatomyositis”. Polymoyositis is also referred to as systemic illness, since it can affect other areas of the body, too. It may be associated with cancer or diseases of other connective tissue. Accordingly, it may be referred to as an “overlap syndrome” or “mixed connective tissue disease”.

People in their 30s, 40s, and 50s are mostly affected by this condition, and it is more common in women and African-Americans.

The signs and symptoms of this condition develop gradually, usually within weeks or months.

There is no cure for polymyositis, but there are medications and physical therapy to help improve your muscle function and strength.

2 Symptoms

Muscle weakness affecting both sides of the body is the main symptom of polymyositis.

The muscles closest to the trunk experience the weakness related to polymyositis, such as the thighs, hips, upper arms, neck, and shoulders. Consult your doctor right away if you feel weakness in your muscles. Many people experience pain or tenderness in the affected areas. The person may have difficulty extending the knee, climbing up or stepping down stairs, lifting things, putting things on a high shelf, or raising the head off the bed when lying down. Polymyositis can also cause inflammatory cardiomyopathy by affecting the heart muscle. If the muscles involved in breathing are affected, a respiratory complication may develop, such as inflammation of the lung tissues.

A general feeling of discomfort, weight loss, low-grade fever, and fatigue may also be experienced by patients. In dermatomyositis, the eyes may be surrounded by a violet discoloration along with swelling. There can be a reddish rash on the face, neck, and upper chest, as well as a scaly, reddish discoloration over the knuckles, elbows, and knees. In childhood dermatomyositis, hard lumps of calcium deposits may develop in the fatty layer of the skin. 

3 Causes

There is no known cause of polymyositis, but it has the characteristics of an autoimmune disorder, in which the immune system attacks healthy tissues. Viruses could be a trigger for autoimmune myositis. People with HIV can develop polymyositis, as well as people with a virus called HTLV-1. People infected with Coxsackie B virus, too, have had cases of myositis. Myositis cases have been reported after exposure to certain drugs like carticaine, penicillamine, interferon-alpha, carbimazole, phenytoin, cimetidine, and growth hormone. Research has suggested that, during pregnancy, mixing of blood cells of the mother and fetus could also later lead to myositis in either of them.

Indicators of genetic susceptibility have been found in some patients.

4 Making a Diagnosis

The doctor will diagnose polymyositis by considering the individual’s medical history and the results of a physical examination.

Making a diagnosis of polymyositis is done by performing several tests.

Consult your doctor if you have muscle weakness. You may be referred to a rheumatologist who specializes in treatment of arthritis and other diseases of the joints, bones, and muscles, or to a neurologist who specializes in nervous system disorders.

Write down all the symptoms you are experiencing, including which muscles are affected, all the supplements and medications you are taking, and if you have any medical problems.

Some of the questions you can ask your doctor include:

  • What is causing my symptoms?
  • What are the other possible causes?
  • Will this change overtime?
  • What kind of tests do I need?
  • What are the possible treatments?
  • What websites do you recommend I check?

Your doctor will also ask you questions, such as:

  • When did you first notice the muscle weakness?
  • Did it develop gradually or suddenly?
  • Are you easily tired during the day?
  • What are the symptoms you are experiencing?
  • Does it limit your activities?
  • Has anyone in your family had the same experience?

The doctor will conduct a physical exam and suggest tests such as:

  • Blood tests: These check if you have increased levels of muscle enzymes, such as aldolase or creatine kinas (CK), that may indicate muscle damage. A doctor who suspects myositis is likely to recommend a blood test in order to check the level of creatine kinase, an enzyme that leaks out of muscle fibers when they are damaged. In polymyositis, its levels are very high. The doctor may suggest blood tests for specific antibodies. These are proteins produced by the immune system in some autoimmune diseases and myositis. Some of these appear to be specific to autoimmune muscle disease. This can also check the specific antibodies related to the symptoms of polymyositis so that your doctor can give you the right treatment and medication.
  • Electromyography: Your muscle will be tested by inserting a thin needle electrode through the skin to confirm if there is a muscle disease and its distribution. A distinctive pattern of electrical activity is shown when a person has inflammatory myopathies. This can help differentiate them from other types of muscle disease.
  • Nerve conduction velocity test: This is sometimes performed to measure how fast the nerve impulse travels.
  • MRI: This checks for inflammation in the muscles that can be seen due to the cross-sectional images of your muscles generated by a powerful magnetic field and radio waves.
  • Muscle biopsy: This can reveal abnormalities in the muscles like infection, inflammation, or damage by removing a piece of muscle tissue that is sent to the laboratory. Generally, in polymyositis, the muscle fibers are invaded by the cells of the immune system. The biopsy can also examine enzyme deficiencies and abnormal proteins.

Sometimes these tests are performed in order to rule out other disorders that mimic the symptoms of inflammatory myopathies. 

5 Treatment

There is no cure for polymyositis. However, there are treatments that can improve muscle strength and function. It is more effective if treated early and will not lead to serious complications. Some people recover completely while others develop episodes of remissions and exacerbations requiring more or less treatment. A low dose of medication is given to those who do not recover completely. Your doctor will offer a treatment strategy based on your symptoms and how well they respond to therapy.

The most common medications for polymyositis are:

  • Corticosteroids: Treatment involves taking high oral-dose prednisone daily, every other day, or as scheduled, or intermittent, short courses of intravenous corticosteroids. This can bring inflammation under control and restore the person’s strength as well as swallowing, breathing, and heart functions. Prednisone works by interfering with the processing of antigens and the early triggering of T and B cell production and proliferation, as well as dampening inflammation and the immune response. Side effects include unwanted weight gain, thinning of the skin, cataracts, bone loss, and redistribution of fat to the face and abdomen and away from the limbs. Corticosteroids like prednisone can control symptoms, but can also result in serious side effects, so your doctor may lower the dosage. The doctor may include one or more medications in order to suppress the damage caused by the immune system.
  • Corticosteroid-sparing agents: Traditional drugs, such as azathioprine (Azasan, Imuran), cyclosporine , cyclophosphamide, and methotrexate (Trexall) decrease the dose and potential side effects of corticosteroids. Some newer drugs, such as mycophenolate mofetil and tacrolimus, are also used.  Risks associated with these medications include flu-like symptoms, low white blood cell count, and liver toxicity. Some are also associated with an increased risk of cancer.

         Azathioprine, mycophenolate mofetil, and Methotrexate interfere with T and B cell proliferation.

         Cyclosporine prevents T cells from stimulating T and B cell production.

         Cyclophosphamide and tacrolimus interfere with the activity and proliferation of B and T cells.

         Hydrochloroquine sulfate, particularly in children, can be used to reduce steroid dosage in myositis.

Your doctor might also recommend:

  • Physical therapy: Exercises to maintain and improve your flexibility and strength. The doctor will advise what level of activities you can perform. Swimming can help maintain strength, and exercise, particularly of the shoulders, will keep the joint supple.
  • Speech therapy: If your swallowing muscles are becoming weak because of polymyositis, this will help you deal with the changes
  • Diabetic assessment: A dietician will teach you to prepare easy to eat foods if you have a hard time swallowing and chewing.

Your doctor may also suggest intravenous immunoglobulin (IVIg), which has healthy antibodies that can block the damaging antibodies that attack muscles in polymyositis. These extra antibodies are believed to confuse the immune system and temporarily lessen the attack on muscles. Previously, plasmapheresis (a blood-cleansing process to remove antibodies) was used, but now, immunosuppressant drugs and/or IVIg treatments are found to be more effective.

  • Infusion of mixed immunoglobulin: This works in many ways, such as providing antibodies against the person’s own antibodies, and interfering with blood-transported chemicals that are released by the immune system, as well as the immune system’s reaction to antibody-marked cells, and the activation and maturation of T and B cells.
  • Plasmapheresis: The antibodies and proteins made by the immune system are removed from the blood and “cleansed” blood is returned to the patient.


If Jo-1 antibody, a myositis antibody, is detected in someone, that person faces an increased risk of developing inflammation of the lung tissues, which can lead to permanent suboptimal lung function. To detect early lung abnormalities, pulmonary function testing can be done. 

6 Prevention

There is no prevention for polymyositis, because its cause is still unclear. Researchers have not yet identified preventive measures to avoid this disease.

7 Alternative and Homeopathic Remedies

Some of the homeopathic remedies for polymyositis include:

  • Arsenicum album
  • Calendula
  • Graphites
  • Lachesis
  • Psorinum
  • Rhus tox

These alternative remedies should be taken with professional advice.

8 Lifestyle and Coping

Try some of these tips to better cope with polymyositis:

  • Know your illness, such as through reading and researching or talking to someone who has a similar condition; ask questions of your doctor or of people who have the same issues.
  • Be involved in your treatment, follow your treatment plan, and consult your doctor if there are new signs or symptoms.
  • Have a good rest and do not push yourself while doing activities, especially when exhausted.
  • Ask for help if you need it and know your limits.
  • Deal with your feelings by staying close to family and friends or by asking for support from them or a support group in your area.

9 Risks and Complications

Some of the possible complications for polymyositis are:

  • Difficulty swallowing (dysphagia): The muscles in the esophagus may be affected, which can lead to malnutrition or weight loss.
  • Aspiration pneumonia: Breathing foods or liquids and saliva into your lungs can lead to pneumonia.
  • Breathing problems, such as shortness of breath or respiratory failure
  • Calcium deposits: These can occur in the skin, muscles, and connective tissue (calcinosis).

Some associated conditions include:

  • Raynaud’s phenomenon: When exposed to cold temperatures, your toes, fingers, nose, cheeks, and ears will turn pale.
  • Cardiovascular disease: You might have myocarditis or inflammation of the muscular walls of the heart, as well as congestive heart failure or heart arrhythmias.
  • Lung disease: You may have interstitial lung disease, which can cause scarring (fibrosis) of lung tissue and symptoms like shortness of breath and dry cough.
  • Other connective tissue diseases: These include rheumatoid arthritis, lupus, scleroderma, and Sjogren’s syndrome.


Scientists are studying the causes of inflammatory myopathies—a group of diseases to which polymyositis belongs—and their underlying mechanisms. Understanding why and how the immune system attacks its own muscle tissue in polymyositis will lead to new tools for diagnosis and better treatment of the disease. 

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