The common causes of swelling under the right side of the ribs are as follows: 1, strain on the intercostal muscles: often due to long hours of ambulatory work, improper sitting posture, such as often twisting the waist and sitting for a long time, easily causing an imbalance in the force on the bilateral intercostal muscles, often leading to strain on one side of the intercostal muscles, which can manifest as soreness and pain in one side of the rib area and ribs; 2, liver disease: swelling and pain under the right side of the ribs may occur due to chronic liver disease, chronic hepatitis, patients should actively carry out liver function tests as well as liver CT, so as to observe the shape of the liver; 3, intestinal flatulence: patients will experience full abdominal distension and pain, distension and pain can sometimes be located in the right quarter rib area.