A: Crestor (rosuvastatin) is a statin, a class of medications used to lower cholesterol and to prevent cardiovascular disease. Common side effects with Crestor include headache, myalgia, abdominal pain, weakness, nausea.: Crestor (rosuvastatin) is a medication used to lower bad cholesterol and to raise good cholesterol. However, it can cause a side effect of leg cramps. This side effect will require a doctor to access if it is a symptom of rhabdomyolysis, which is when the muscle fibers break down.