Question: What are the side effects of taking Simvastatin?

Answer: Simvastatin (brand name Zocor) is a prescription medication used together with diet, weight-loss, and exercise, to lower LDL cholesterol, known as "bad cholesterol", and triglycerides in the blood. It has also been shown to increase HDL, or "good cholesterol". Simvastatin is in a class of medications known as HMG-CoA reductase inhibitors, or more commonly, "statins". Millions of Americans are taking statins to prevent heart attacks and strokes.

For the most part, statins are safe drugs with few side effects. Some people have stomach upset, gas, heartburn, and constipation or diarrhea with their statin. If you have these symptoms, take your statin in the evening with dinner. If these side effects become severe or don't go away, talk to your doctor.

More serious, but less common side effects include liver problems, cognitive impairment (memory loss and problems thinking), high blood sugar leading to the development of Type 2 diabetes, and muscle damage.

Liver problems. Before you take your statin, your doctor will likely check your liver function with a blood test. While taking this medication, tell your doctor if you have symptoms that include unusual fatigue (tiredness), loss of appetite, pain or discomfort in the right, upper part of the stomach, and yellow eyes or skin, and dark urine (pee). Also tell your doctor if you have a rash or itching.

Memory loss and problems thinking. There have been reports about memory loss, forgetfullness and confusion with statin use. While these experiences are rare, those affected report feeling "fuzzy" or unfocused in their thinking. For the most part, the symptoms were not serious and went away within a few weeks after stopping the statin. Tell your doctor if you feel confused, forget things, or have clouded thinking.

A small increased risk of raised blood sugar levels and the development of Type 2 diabetes have been reported with the use of statins. Your doctor might check your blood sugar before and after you start your statin. Tell your doctor if you have increased thirst or hunger, or weight loss. Also tell your doctor if you have blurred vision or are peeing more.

Sore muscles can be a sign of muscle injury. Severe muscle injury, called rhabdomyolysis, can cause your kidneys to shut down (kidney failure) if not treated. This is a rare but extremely serious medical condition. All statins carry some risk of muscle injury, but the risk is higher for people who take the 80 mg doses of simvastatin, the highest approved dose of simvastatin.  Tell your presciber if you have unexplained muscle pain, soreness, or weakness, or trouble moving your arms or legs. This is very important if you also have a fever, a sick feeling, or dark colored urine.

Some medications interact with statins in a way that increases the risk of statin muscle damage. Before you take a new medication, tell your doctor and pharmacist you are taking a statin so that they can check for interactions. Alcohol can increase the risk of serious side effects. Grapefruit and grapefruit juice have also been known to interact with statins. Ask your doctor about the safe use of these products while you are taking simvastatin.

No medicine provides benefits without some risk of side effects. Statins have been very effective in preventing heart disease, but they need to be taken with care. Always talk to your doctor if you have bothersome side effects. Switching to a different statin or lowering the dose can help with some side effects.

Last Updated: November 24, 2013