Commonly prescribed brands:
How it is given:
What it is used for:
Combined with diet, to reduce total cholesterol level, to lower triglyceride levels, and to increase HDL (good) cholesterol
You should not be treated with it if:
You have been diagnosed with:
Possible side effects:
Flushing (primarily in the face and neck), hot flashes, nausea, indigestion, gas, vomiting, diarrhea
OTC = over-the-counter
What is niacin?
Niacin is a form of vitamin B3 commonly found in meat, fish, legumes (peanuts), bread, and fortified breakfast cereals. Another form of vitamin B3 called nicotinamide is often confused with niacin, but it does not affect cholesterol levels. Niacin or nicotinic acid is the most effective medication for raising HDL (good) cholesterol. It is not clear exactly how niacin works. It seems to prevent the breakdown of the carriers for HDL cholesterol in the blood (called high-density lipoproteins).108 As a result, HDL cholesterol levels are increased in the blood. Niacin also decreases the production of the carriers for triglycerides in the blood (called very low-density lipoproteins). As a result, triglyceride levels are reduced.109 Triglycerides are another type of lipid, or fat, that can raise your risk of heart disease.
What types of niacin are available?
There are three types of niacin available:
- Immediate-release or crystalline niacin is available over-the-counter, sometimes sold as vitamin B3 or simply niacin, or as the prescription drug Niacor
- Long-acting niacin is sold over-the-counter. It is also called sustained-release or timed-release niacin
- Extended-release niacin is only available by prescription as Niaspan
How does niacin affect my cholesterol levels?
Niacin is the most effective cholesterol medication for increasing HDL cholesterol, raising it twice as much as the fibrate gemfibrozil.110 A 1 to 2 g daily dose of niacin raises HDL cholesterol by 20% to 30% in men and women.110-113 Immediate-release niacin appears to be more effective than long-acting formulations, and just as effective as extended-release niacin at raising HDL cholesterol.114, 115 Niacin also lowers triglycerides by about 15% to 35% at doses up to 2 g per day.110, 111, 116-118
Niacin does not consistently lower levels of LDL (bad) cholesterol. Some studies show reductions of about 20%,111, 113, 116, 118 and others have found no LDL cholesterol-lowering effect for niacin.110, 119 Because of the side effects (see below), a maximum dose of 2 g per day is generally recommended for niacin. It may be that higher doses are required to significantly lower LDL cholesterol in some people. Dose for dose, niacin lowers LDL cholesterol more in women than in men.118, 120, 121 Niacin may be combined with an LDL cholesterol-lowering medication (usually a statin). Even if niacin doesn't actually lower LDL cholesterol, it can make it less likely to clog your arteries.122 Small dense LDL particles are more likely to clog your arteries than larger particles. Both extended-release and immediate-release niacin increase the proportion of larger particles compared with smaller ones.115 Additionally, niacin is the only cholesterol medication that lowers lipoprotein(a), or Lp(a), a type of LDL cholesterol that is associated with an increased risk of heart disease. Niacin can lower Lp(a) by 15% to 35% at doses of 1.5 to 2 g per day.110, 111, 115, 118 It is not yet known whether lowering Lp(a) reduces the risk of having a heart attack or dying from heart disease.
Does niacin prevent heart attacks or dying from heart disease?
Niacin does not appear to reduce the risk of dying from heart disease.73 In men with heart disease, niacin reduced the risk of having another heart attack within five years.123 There have been no similar studies conducted in women.
Why do I need to take niacin and a statin?
Niacin is often used in combination with statins because the two medications affect different types of cholesterol. Statins lower LDL cholesterol, and niacin raises HDL cholesterol. One small study suggested that women taking a statin and immediate-release niacin have greater reductions in LDL cholesterol than men.120 Combined statin and niacin improves cholesterol and triglyceride levels more than a statin alone; however, it has more nuisance side effects.124-127 In contrast to fibrate/statin combined therapy, there does not appear to be an increase in the risk of serious side effects when statins and niacin are taken together.93, 128
Does combined niacin/statin therapy prevent heart attacks?
In studies in men, niacin combined with a medication to lower LDL cholesterol (a statin, fibrate, or bile acid resin), slowed the buildup of fatty plaque in the arteries of the heart.129-132 It is not known whether combination therapy with niacin and statins can lower the risk of having a heart attack or dying from heart disease. One study of around 550 men and women found that combined fibrates and niacin reduced the risk of the risk of dying early by 26%.85
What is the “ niacin flush” side effect?
The risks and side effects vary for the different types of niacin. The common nuisance side effect is the “niacin flush” characterized by warmth, redness, tingling, and possible itching in the face, neck, and chest. While this side effect is unpleasant, it is not serious. Flushing tends to occur shortly after you take your niacin dose and can last for a few hours. It is a particular problem with immediate-release niacin because of its rapid absorption and multiple daily doses (usually 2 or 3 pills per day). Flushing is less of a problem with long-acting niacin because it is generally absorbed over 12 hours and the niacin is slowly released into the bloodstream. Absorption rates and number of daily doses vary between long-acting products and preparations. Extended-release niacin (Niaspan) is absorbed over 8 to 12 hours, more quickly than long-acting niacin.133 However, because it is taken only once a day at bedtime, niacin is released when you are asleep and less likely to experience or notice flushing.134 To counteract the side effects of flushing and skin irritation, you can take a low-dose aspirin or non steroidal anti-inflammatory drug (such as Aleve, Advil, or Motrin) 30 minutes before your niacin dose. Hot drinks and alcohol should be avoided around the time of your niacin dose. You are less likely to experience flushing after several weeks of continued niacin use.116, 135
What other side effects does niacin have?
Niacin can cause liver problems particularly at high doses.114, 136 Long-acting preparations have a higher risk of liver problems, including liver failure and hepatitis, than the other niacin preparations.114, 137-139 Your healthcare provider will run blood tests to check for liver problems periodically. The risk of liver problems also increases if you switch between the different types of niacin without taking the proper precautions (see below).
Niacin may also affect blood sugar levels particularly at high doses (3 g per day), which can cause problems for people with diabetes.140, 141 Lower doses of extended-release niacin (1 to 1.5 g per day) slightly increased blood sugar levels in people with diabetes in one study.142 However, these blood sugar effects were easily controlled when patients adjusted the doses of their diabetes medications.
A maximum daily dose of 2 g is generally recommended for all niacin preparations because this provides the best HDL cholesterol and triglyceride benefits while minimizing the risk of serious side effects.
Do men and women experience the same side effects?
One study found that women tended to experience more side effects than men with extended-release niacin, especially at higher doses (above 2 g).118 Another found that women and men both experienced flushing, but that women reported more nausea, vomiting, lack of energy, and rash than men. Men were more likely to report flu-like symptoms.121 To reduce the risk of gastrointestinal side effects, you can take niacin with a low-fat snack.
What is dose titration and can I switch between niacin preparations?
To reduce the number and severity of side effects, niacin doses are titrated. That means you start out taking a low dose (usually 500 mg) and gradually build up to the dose that's most effective for you (usually 2 g maximum). Your daily dose should not increase by more than 500 mg over a four week period. You should not switch between the different types of niacin without consulting your healthcare provider. When switching, you may have to start at a lower dose than you are used to and work up to a higher dose of the new formulation. Switching between immediate-release and long-acting niacin without taking the proper precautions can cause severe liver problems. Because there is some variation between the different long-acting niacin formulas, you should not switch between different brands.72