How statins cause muscle pain is not fully understood. One theory is that statins may affect a protein in muscle cells, which decreases muscle growth. Another theory is that statins decrease the levels of a natural substance in your body called coenzyme Q10. This substance helps your muscles produce energy. With less energy, your muscle cells may not be able to work properly.

Either of these actions may cause:

• muscle pain
• muscle fatigue
• muscle weakness

Tasks that were once simple, such as climbing stairs or walking, may make you uncomfortable and tired while using statins.

Muscle breakdown

Rhabdomyolysis, or the breakdown of muscle tissue, is a rare side effect of statins that can also cause muscle pain. This disease can cause life-threatening muscle damage. In addition to severe muscle pain, rhabdomyolysis can lead to liver damage, kidney failure, and, in rare cases, death.

According to the FDA, the following statins contain specific warnings on the package inserts about muscle pain and rhabdomyolysis:

• lovastatin extended-release (Altoprev)
• rosuvastatin (Crestor)
• fluvastatin (Lescol)
• atorvastatin (Lipitor)
• pitavastatin (Livalo)
• lovastatin (Mevacor)
• pravastatin (Pravachol)
• simvastatin (Zocor)

Rhabdomyolysis sounds scary, but the average statin user does not have to worry about developing this disorder. However, taking high doses of statins or taking them with certain other drugs can increase your risk of this condition. If you're concerned, be sure to talk to your doctor about your risk.