Early manifestations of polymyositis are usually symmetrical proximal muscle weakness and tenderness in the extremities. Polymyositis is a kind of non-purulent inflammatory myopathy of the transverse muscle caused by various reasons leading to the abnormality of the immune system of the body. Clinically, it is mainly characterized by symmetrical weakness of the proximal limbs and cervical and pharyngeal muscles, and muscle tenderness. Early symptoms of polymyositis are usually symmetrical proximal limb muscle weakness and tenderness, such as difficulty in walking up stairs and squatting, and inability to raise both arms. As the disease progresses, it gradually involves the neck muscles, pharyngeal muscles, respiratory muscles, etc., and patients may have difficulty in lifting their head, difficulty in swallowing, difficulty in breathing and other corresponding manifestations, and in the late stage, they may even experience muscle atrophy. If patients are suspected of suffering from polymyositis, it is recommended to carry out standardized treatment in time to avoid delaying the condition.