Atorvastatin may cause muscle pain, tenderness, or weakness in some people. This side effect does not occur in every patient, but it is an important issue to monitor in statin users. Mild muscle discomfort may be observed, while severe pain, widespread weakness, fever, or dark-colored urine should be evaluated for possible serious muscle injury. In such cases, the medication should not be stopped without consulting a physician. The doctor may order blood tests to check muscle enzyme levels if necessary.