Having a fluid buildup in the shoulder may cause the following consequences. First, it may lead to continuous shoulder pain. In the early stage of fluid accumulation inside the shoulder joint, it will manifest as soreness and pain inside the shoulder joint. As the condition progresses, it may lead to persistent soreness and swelling of the entire shoulder joint, which may increase when it is cloudy or rainy, or when you are overworked. Secondly, it may lead to a decrease in shoulder joint mobility. When a shoulder joint effusion occurs, the patient may not move because of fear of pain, which may cause a significant decrease in shoulder joint mobility over time, and a very stiff feeling in the shoulder joint movement. Thirdly, the muscle strength of the shoulder may be greatly reduced, which is also caused by the pain in the shoulder and the long-term inactivity of the shoulder joint. Fourthly, the muscles around the joint may atrophy. The patient may not move the shoulder joint due to long-term pain, which may cause the muscles of the shoulder joint to gradually atrophy.