Respiratory acidosis may be a serious problem. It is most often caused by some other illness. It happens when your lungs cannot get rid of all of the carbon dioxide that your body makes. Then your blood has a higher acid level. Sometimes your lungs do not work well enough to get rid of the carbon dioxide. Other times, your body makes too much, and it is hard for your body to get rid of the extra carbon dioxide. Your doctor will work to find the cause of your respiratory acidosis and treat the problem.