Myalgia and Myositis Explained

When we head to the doctor for a diagnosis and description of our condition, we will often hear a lot of words that we don’t completely understand that refer to us. This can be a little unsettling and it can certainly help us in our recovery and in our understanding if we have a better grasp of some of the words being used.

Two of the most common expressions we might encounter during a visit to the doctor are ‘myalgia’ and ‘myositis’. Here we will examine what those terms mean, some of the possible causes and implications and any other relevant information.



Myalgia broadly means ‘muscle pain’ and is a symptom of many different diseases and injuries. Myalgia for instance can be used to describe the main symptom of a pulled muscle in which the muscle fibers are ripped in large quantities and this then results in pain and lack of mobility. Other causes however can be illnesses and conditions and particularly in the case of chronic myalgia – and this can include such conditions as chronic fatigue syndrome, or viral infection.


Meanwhile myositis means ‘inflammation’ of the muscles. Like myalgia it is not a term that describes a condition but rather one that describes the symptom and likewise it can be a sign of injury, or a side effect from a condition.


In the case of myalgia, the most common causes are injuries such as strains, hematoma, tension etc. Anything that causes a tear or a bruise in the muscle of course will cause pain. This can also occur due to over use – use for long durations (repetitive strain injury) or with too much resistance.

However this causes localized and acute myalgia. Where the condition affects the whole body and chronically then it may be more likely to be an illness. Muscle pain is very likely to occur as a result of infection, and these include: influenza (AKA the flu), Lyme disease, malaria, hemorrhagic fever, polio, dengue fever etc.

Likewise myalgia is caused by a range of autoimmune disorders and these can include systemic lupus erythematosus, polymyositis, multiple sclerosis and others. In some cases myalgia may be the result of a medication – such as fibrates, statins, cocain and others.

Myositis has similar causes. Most often the cause of myositis is an autoimmune condition, though in some cases it may also be caused by infection (though this is rarer). It can also be a side effect of some drugs such as statins.

Here we will look at the treatment and symptoms for some particular causes:

Autoimmune Conditions

An autoimmune condition such as polymyositis can cause chronic inflammation of the muscles and pain. Symptoms are pain along with weakness and loss of muscle mass. This particularly affects the hip extensors which can create difficulties with climbing stairs or standing up from a seated or prone position. The skin will often thicken in certain areas such as the fingers and hands, and you might also experience difficulty in swallowing and fever. Dermatomyositis and polymyositis are correlated with certain cancers. The exact causes and etiology of many of these conditions are unknown and might be a result of genetics, viruses and others. In some cases an initial injury may prove to be the catalyst for the condition. The condition is usually treated with steroids in high doses, and immunosuppressants can also be effective. After around 4-6 weeks some muscle strength should return, and daily exercise may also prove useful. However polymyositis is a life-long condition and in severe cases it may result in permanent disability or even death.


In the case of infection the myalgia and myositis will be a side effect of the infection. This is the case in conditions such as influenza (the flu) but also Lyme disease and many others. Other symptoms will usually be weakness, lethargy, nausea, fever, sweating and in some cases localized discoloration. The best treatment is normally antibiotics, though in some cases other forms of treatment will be used.


Many injuries can result in myalgia and myositis. If you should pull or strain a muscle for instance then this will often result in muscle pain and swelling. The best way to treat the condition is usually with rest and elevation along with the application of a cool pack (for no more than 20 minutes) and compression.


  1. I liked the article, but I have a question. Can my back pain be because of extra tension? I do have flu but I have had flu all the time almost (like throughout the year), but this pain has never occurred before but today it is like very painful can't sit straight and even laying down is hurting.

    Please email some advice. Thank you!

  2. The article was extremely helpful. It explains in a very clear language the words used by the doctors. My mind is more at ease knowing the exact meaning of the words. Sometimes the doctor's words don't sink in until we reach home and read his report on the visit. Thank you and keep up the good work.


  3. Margaret Simone Cinelli

    This article was very helpful. Thank You!

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