Niacin and simvastatin are two medications used to lower cholesterol. Simvastatin belongs to a class of drugs called HMG Co A reductase inhibitors or statins. It reduces bad cholesterol while increasing good cholesterol. Niacin is vitamin B3 and when given in large doses can lower triglycerides and bad cholesterol. Niacin also helps to increase good cholesterol. These medications are also used in patients who have had heart attacks or strokes caused by atherosclerotic disease. Both medications can have significant side effects.
Flushing
According to RxList.com, flushing occurs in 88 percent of patients taking niacin. Flushing is the sudden feeling of warmth, redness, tingling or itching that occurs shortly after taking the medication. Occasionally flushing is accompanied by increased heart rate, dizziness, palpitations, shortness of breath and/or sweating. It is not a well understood phenomenon, but flushing may occur due to the release of prostaglandins which dilate blood vessels which leads to redness of the skin. Histamine release is thought to cause the tingling and itching sensation. Flushing may be exacerbated by alcohol, aerobic activity, sun exposure or consumption of spicy foods, according to the Merck Manual Online Medical Library.
Liver Enzymes
Statins are the drug of choice to lower LDL cholesterol or "bad" cholesterol, according to the Merck Manual. They are proven to reduce cardiovascular mortality in multiple studies. Adverse effects are relatively uncommon but elevated liver enzymes is one potential side effect. Liver damage is more likely when taking combination medications such as niacin and simvastatin together. Mild elevations in liver enzymes do not preclude taking the drug. High elevations may require cessation of the medication. Patients on statin drugs should have their liver enzymes checked every six weeks or so in order to prevent irreversible damage.
Statin Myopathy
Muscle pain or statin myopathy can occur when taking simvastatin. Severe problems can occur when muscles break down and release myoglobin into the blood stream. This is called rhabdomyolysis and can potentially damage the kidneys if severe, according to MayoClinic.com. Muscle toxicity is more common when taking other medications that interfere with the P3A4 enzyme. Medications such as erythromycin, gemfibrozil, niacin and anti-fungal agents can exacerbate statin myopathy.
