Muscle complaints are the most common side effect of statins. These can include pain, severe weakness, easy fatigability, and in rarer instances, rhabdomyolysis, which can be fatal.

While proponents of statin safety claim muscle disorders are rare, the literature says different. In a study of 22 professional athletes who were taking statins, 77 percent stopped their treatments with the medication because they experienced muscle pain and weakness.

Proponents of statin safety also claim that muscle damage from the drugs is rare, and only seen when blood creatine kinase levels (a measure of muscle damage) are 10 times higher than normal. Yet in a study in which muscle biopsies were taken from statin users complaining of muscle pains, researchers found pathological signs of muscle damage even though blood creatine kinase levels were perfectly normal.

Some patients are so weakened by statins that they are no longer able to function, causing some to have to stop working. In most cases, if use of statins is stopped early, muscle symptoms subside.