Shoulder pain after fever is usually due to: First, after fever the body will release inflammatory mediators, conventional inflammatory mediators including interleukins, leukotrienes, inflammatory mediators 2, inflammatory mediators 4, tumor necrosis factor, etc., such mediators in the body temperature when the release of the obvious, will cause the skin, joints, muscle pain, especially in the shoulder joint pain is more obvious. Secondly, the body will experience lack of oxygen when fever occurs, and the lactic acid and histamine in the body will increase significantly when lack of oxygen, which will also cause pain in the joints. Thirdly, lactic acid will accumulate significantly in skeletal muscles during fever, such as biceps and triceps, which will also lead to shoulder pain when it accumulates. Fourthly, viruses, bacteria or other pathogenic microorganisms that produce a pyrogen and cause an immune complex reaction can also lead to shoulder pain after a fever.