I must start with a warning. If you are taking a medication for whatever reason and learn it has a possible side effect, do not stop taking the drug without informing your doctor.

Many people have stopped taking osteoporosis and diabetic drugs and various antidepressants because of reports in the news of serious side effects. This is a big mistake! And now the Food and Drug Administration has insisted that new warning labels be added to all of the statin drugs that are used to lower cholesterol. New evidence indicates that these drugs rarely lead to memory loss or precipitate or aggravate diabetes.

Currently, 33 million Americans are taking statins to lower the risk of a heart attack by decreasing the level of the bad (LDL) cholesterol. In numerous studies, the number of heart attacks has decreased by 25 percent to 30 percent. This particularly applies to people who are at high risk of having a heart attack, such as people who have a strong family history of heart disease, have high blood pressure, smoke cigarettes, are diabetics, or have had a previous attack.

In addition to the benefits of statins, there is suggestive — but not proved — evidence that lowering cholesterol may decrease the risk of Alzheimer's disease, prevent depression and even prevent bone fractures. No wonder they are widely referred to as miracle drugs.

For this reason, experts in the field believe more of us should be taking statins. In some European countries, it is available over the counter. In the United States, generic statins are inexpensive ($10 for a three-month supply).

But statins do have some side effects that limit their usefulness. The most serious is significant muscle tenderness and inflammation. This can impair quality of life and be severe enough that taking the medication becomes impossible. Muscle problems are more common in women, older people, diabetics, alcoholics, and those who take medications that interfere with statin metabolism. For many, the symptoms are tolerable, and despite their presence, there is little harm in continuing treatment.

Just as important is liver damage, which affects about 7 percent of those who are prescribed a statin. The damage to the liver is temporary and is resolved as soon as the drug is discontinued. Whenever a statin is prescribed, cholesterol and liver-function tests must be repeated after six weeks. On occasion, the dose of the statin will need to be increased. The drug should be discontinued if abnormalities in liver function are identified. If liver tests are normal, they should be repeated again after one year on statin therapy.

Rarer side effects include gastrointestinal upset and insomnia that, on occasion, could be severe enough that taking the statin becomes impossible.

What about the new warnings? How common are they? Who should be concerned? Fortunately, statins very rarely cause either memory loss or diabetes. In pre-diabetics, statins may be the last straw that forces the need for therapy to lower blood sugar. However, if diabetes or pre-diabetes is appropriately controlled with diet, exercise and medication, the benefits of lowering cholesterol far outweigh the risk of a higher blood sugar.

Memory loss is more of a problem. We do know that lowering cholesterol appears to reduce the risk of memory loss and may slow the rate of progression of the disease. For those with very early symptoms who have never been treated with a statin, the benefits may well make treatment worth it. For those on statins with minimal memory loss, a trial of the drug should be considered to assure that the statin is not the cause. And its use in those with moderate to severe memory loss is questionable at best.

Also, if a person is perfectly healthy, with no risk factors for having a heart attack, the use of statins could be of little value. Studies conducted by Cochrane Review that carefully analyzed 14 clinical trials of statins in healthy individuals showed that they did not prolong life, and the reductions in the number of heart attacks were insignificant.

So if you are concerned about statins, speak to your doctor.