Muscle pain, and it has one other known side-effect which you would be well-advised to deal with in your own way: statins interfere with the body's ability to make its own co-enzyme Q-10, which is important for muscle health, notably heart muscle health (myocytes). Although the research isn't what could be called strong on this, there is sufficient doubt that people are often advised to supplement with CoQ-10, between 100-200 mg each day. This is something you might wish to discuss with your GP or with a cardiologist.

Note, also, that there are two common formulations of the drug: ubiquinone (with '-one' on the end) and ubiquinol (with '-ol'). The latter is the most easily taken up and used by the body, but it is also the most expensive. Costco sells it for a reasonable price if you're interested.