The most common polymyositis symptom is muscle weakness, according to MedicineNet. The muscles may ache, and the area may feel tender. Some patients experience fatigue, low-grade fever, weight loss and general discomfort.
Polymyositis causes the gradual or rapid weakness of muscles close to the trunk, reports Mayo Clinic. It mostly affects muscles in the thighs, upper arms, hips, shoulders and neck. The muscle weakness affects both the right and left sides of the body. The patient may have problems rising from a seated position, reaching overhead, extending the knee, climbing stairs or lifting objects, explains the National Institute of Neurological Disorders and Stroke.
Some polymyositis patients may experience shortness of breath, arthritis, heart arrhythmia and difficulty speaking or swallowing, according to NINDS. As the disease progresses, it may affect distal muscles in the wrists and ankles and cause severe respiratory problems.
Skin involvement symptoms include reddish discoloration on the elbows, knees and knuckles, reports MedicineNet. The patient may have swelling and violet discoloration around the eyes. He may also have a reddish rash on the chest, face or neck. Lung and heart involvement may lead to serious complications, such as heart failure, irregular heart rhythm and inflammation of the lungs.