"Side effect" is a grossly misleading term since it implies that a drug is doing something that it should not be doing, something that it does not always do. But no chemical substance knows what we want it to do, it just performs its chemical functions.

... statins lower blood levels of cholesterol, as we desire. But they also inhibit production of ubiquinol (coenzyme Q10), which is an essential participant in generating energy; for that reason, muscle weakening is an inevitable "side" effect of using statins. Many sources — but chiefly unofficial ones — advise the use of CoQ10 supplements by every one who is taking a statin. Drug companies, however, do not do so, apparently for commercial or legal reasons. One of this author's personal friends, quite a distinguished researcher whose expertise is in biochemistry, aging, and the role played by ubiquinol, once made a formal proposal to a drug manufacturer that a combination of a statin with CoQ10 could be marketed as a "super statin" that lacks the normal muscle-weakening effect of statins. The manufacturer's scientific staff were enthusiastic about the idea, but the legal department exercised a veto because this would have admitted implicitly that the company had not in earlier years issued appropriate warnings about muscle-weakening "side" effects.