Niacin is a B vitamin that may raise your HDL ("good") cholesterol. But side effects might outweigh benefits for most people.

By Mayo Clinic Staff

Niacin, a B vitamin, has long been used to increase high-density lipoprotein (HDL) cholesterol — the "good" cholesterol that helps remove bad cholesterol from your bloodstream.

But niacin isn't for everyone. People who take niacin in addition to common cholesterol medications see very little additional benefit. And niacin can cause uncomfortable and sometimes dangerous side effects.

Niacin (nicotinic acid) is a B vitamin that's used by your body to turn food into energy. Niacin also helps keep your nervous system, digestive system, skin, hair and eyes healthy. That's why niacin is often a part of a daily multivitamin, though most people get enough niacin from the food they eat.

When it's used as a treatment to increase your HDL cholesterol or correct a vitamin deficiency, niacin is sold in higher doses that are prescribed by your doctor. Prescription-strength niacin includes such drugs as Niacor and Niaspan.

Niacin is also available as an over-the-counter supplement. Supplements sold over-the-counter are not regulated like prescription medications. The ingredients, formulations and effects of over-the-counter niacin can vary widely.

Don't take niacin without discussing it with your doctor first because niacin can cause serious side effects when taken in high doses.

Niacin can raise HDL cholesterol by more than 30 percent. HDL, the "good" cholesterol, picks up excess bad cholesterol in your blood and takes it back to your liver for disposal.

Cholesterol levels are measured in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L):

  • For men, HDL levels under 40 mg/dL (1 mmol/L) increase the risk of heart disease.
  • For women, HDL levels under 50 mg/dL (1.3 mmol/L) increase the risk of heart disease.

High-dose niacin can cause stomach upset and make your skin flush or itch. More importantly, niacin can increase your risk of:

  • Bleeding
  • Diabetes
  • Infection
  • Liver damage
  • Stroke

In the past, it was thought that HDL levels would increase even more if niacin was added to cholesterol medications called statins, such as atorvastatin (Lipitor) and simvastatin (Zocor). But recent studies indicate that niacin provides little additional benefit when compared with statins alone.

Most doctors no longer recommend niacin for first-line cholesterol control — except for people who can't tolerate statins. In those people, the increase in HDL may outweigh the risk of potentially serious side effects.

Lifestyle changes also are helpful in boosting HDL:

  • Stop smoking if you are a smoker.
  • Eat a healthy diet.
  • Start an exercise program, with your doctor's OK.
Aug. 12, 2014