Statins have few known side effects. They are capable of damaging the liver and muscles, but such problems are rare and usually not serious. One statin drug, cerivastatin (Baycol), however, was voluntarily removed from the market in 2001 because its use was associated with multiple occurrences of rhabdomyolysis, a condition characterized by muscle cell damage that can lead to kidney failure and, very rarely, death.

Rhabdomyolysis is a potential adverse effect of all statin drugs, and the risk seems to be significantly higher in patients who take statins in combination with fibrate drugs. If you take this duo, you and your doctor should watch for persistent muscle aches and pains, which could indicate a predisposition to rhabdomyolysis.

About five of every one hundred people who take a statin report having muscle pain. However, not all of these complaints are because of statins. It sounds confusing, but in large trials on statins, muscle pain was reported by nearly as many people taking a placebo as were taking the active statin drug.

Still, some people have muscle aches right after starting a statin that go away when they stop taking it. About eight of every ten thousand people who take a statin develop severe muscle pain or weakness. Stopping the drug almost always makes the problem disappear.

Some physicians routinely measure the levels of muscle protein in the blood, called creatine kinase (CK or CPK), to look for early signs of statin-induced muscle injury. I don’t find the test of much value. Patients on statins can have muscle pains without CK elevations, and they can have CK elevations in the absence of muscle pain, even when not taking a statin.

Asking patients about their muscle symptoms has been the best way for me to determine if the statin is causing a problem. If we are unsure, we stop the drug for a while and see what happens. The blood test can’t give a definite answer, but, most often, a careful conversation between the doctor and the patient can.

Another potential effect of statins is an alteration in the liver function tests. This side effect is the one that most patients have heard of and the one they worry about the most. This worry is unwarranted, in my opinion. Up to two of every one hundred people who take a statin have higher-than-normal blood levels of liver proteins called transaminases (pronounced trans-AM-ehnase).

It’s not clear if a small increase signals a real problem. An American Heart Association advisory on statin safety calls statincaused liver failure “exceedingly rare.” While I think it is prudent to have a liver test done about once a year when taking a statin, that may be more cautious than necessary.

Elevated liver transaminases caused by statins usually revert to normal in days or weeks after stopping the drug, so even an abnormal set of liver tests is no cause for alarm. Statins can also make people drowsy, constipated, or nauseated, but these side effects are quite uncommon.

The United Kingdom even recently decided that one statin, simvastatin, was safe enough that it could be provided as an over-the-counter (nonprescription) drug. The U.S. Food and Drug Administration is reviewing that option for several statins in this country.

Because statins are relatively new medications, it’s hard to know for sure what the statins’ long-term effects will be. Longterm studies on statins are critical because people will probably take these drugs for decades. The first such analysis offers some reassurance.

A decade-long study from Sweden showed that the side effects of simvastatin (Zocor) were limited to minor, temporary changes in liver enzymes circulating in the bloodstream. The relatively high risk of coronary disease in most middle-aged and older Americans tips the scale in favor of long-term statin use.

For most teenagers and young adults, the risk of coronary disease in the short term is lower, making it reasonable to treat these younger folks less aggressively most of the time. It is important to note that statins have been shown to cause fetal malformations in embryos of test animals, so no woman of childbearing age should take the drugs without taking measures to avoid pregnancy.