Symptoms Polymyositis (PM) and dermatomyositis (DM)

Muscle weakness is common and mainly involves the ‘proximal’ limb muscles (the muscles around the shoulders, upper arms, pelvis and thighs). This sometimes comes on rapidly, over a period of days, but usually over months or even years.

The pattern of weakness means that some people struggle to climb stairs or get up out of chairs. With the arms, there is often difficulty lifting or using the hands with arms elevated, for example in reaching overhead cupboards or with washing hair.

A few people may experience muscle pain, particularly where the onset of symptoms is quick. Sometimes there can be aching, discomfort, or mild tenderness of the affected muscles.

Myositis can cause swallowing difficulties and can affect the breathing muscles (including the diaphragm), heart or the lungs. If you experience shortness of breath, chest pains, palpitations, or changes in your breathing, discuss this with your GP or specialist.

The skin is affected in DM, usually by a rash, on the face, exposed parts of the chest, and hands (knuckles and nail beds). Exposure to sunlight can make the rash worse. People with anti-synthetase syndrome can also experience skin changes, particularly cracking of skin on the side of the fingers (called ‘mechanics’ hands’).

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