Myositis is the inflammation of the skeletal muscles, also known as voluntary muscles. “Myo” means muscles while “itis” means inflammation. This is a rare disease usually triggered by autoimmune conditions. Autoimmune diseases occur when the immune system attacks the healthy tissues of the body.

Myositis can be caused by five things: inflammatory conditions, infection, drugs, injury, and rhabdomyolysis. Inflammatory conditions like dermatomyositis and polymyositis inflame the muscles throughout the body. Myositis caused by this factor is deemed as the most serious form and it requires immediate and extensive treatment.

Viral infection is the most common type of infection that leads to myositis. Bacterial and fungal infection may also bring about muscle inflammation. There are also certain drugs that cause temporary muscle damage. Examples are statins, colchicine, plaquenil (hydroxychloroquine), alpha-interferon, and cocaine.

Injury to the muscles can result not only in muscle swelling but also in pain and weakness. Proper rest is recommended for these cases. Lastly, rhabdomyolysis refers to the condition in which muscles break down and produce muscle swelling and pain.

Treatment for myositis vary according to the cause. For example, myositis caused by inflammatory conditions are treated with medications that suppress the immune system such as Prednisone, Imuran (azathioprine) and Methotrexate.