Som andre HMG- CoA reduktasehæmmere, forårsager Simvastatin ind imellem myopati, der manifesterer sig som muskelsmerter, ømhed eller muskelsvaghed med kreatininkinase (CK) over ti gange den øvre normalgrænse (ULN).
Myopathy/ Rhabdomyolysis Simvastatin, like other inhibitors of HMG-CoA reductase, occasionally causes myopathy manifested as muscle pain, tenderness or weakness with creatine kinase (CK) above ten times the upper limit of normal (ULN).