Niacin dosage, forms, and strengths

Niacin is vitamin B3, a water-soluble B vitamin. Many foods contain niacin, particularly meat, fish, and cereals. Niacin is usually found in multivitamins and B complex vitamins, though it can be purchased as a separate dietary supplement. A healthcare professional may prescribe high-dose niacin supplements to people with niacin deficiency or to improve cholesterol and fat (triglyceride) levels in the blood. In supplements and pills, niacin usually comes in different chemical versions, like nicotinic acid and niacinamide (nicotinamide). The body converts these forms of niacin into niacin enzymes (NAD and NADP). These enzymes are responsible for hundreds of important chemical reactions throughout the body. 

RELATED: 9 benefits of niacinamide

Niacin forms and strengths

Vitamin B3 is usually taken orally and can be purchased over the counter or in prescription formats. 

• Tablet: 50 mg, 100 mg, 250 mg, 300 mg, 500 mg, 750 mg, 1000 mg

• Extended-release tablet: 250 mg, 500 mg, 750 mg, 1000 mg

• Capsule: 100 mg, 250 mg, 400 mg, 500 mg

• Extended-release capsule: 500 mg, 1000 mg

• Powder for mixture with food: 500 mg/serving,1000 mg/serving, customizable

Niacin dosage for adults

Niacin is a necessary nutrient. Most people get enough dietary niacin, so they don’t need to supplement it. Healthcare professionals prescribe high doses of niacin for those with niacin deficiency and high cholesterol or to prevent cardiovascular disease. Healthcare providers do not prescribe niacin to people with active liver disease, active stomach ulcers, or arterial bleeding, as it can cause serious problems, including liver injury.

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Niacin dosage for supplementation

Most people get the recommended daily allowance (RDA) of niacin from eating everyday foods like meat, fish, and fortified cereals. People should not take more than the recommended daily allowance of niacin unless advised by a healthcare professional. The upper tolerable limit (UL) of niacin is 35 mg daily. High-dose niacin requires the supervision and medical advice of a healthcare provider, as high doses can cause severe adverse effects, including liver damage.

In some cases, a healthcare provider may suggest higher doses of niacin for people with certain medical conditions, including pregnancy, breastfeeding, eating disorders, drug use, alcoholism, and digestive system problems. 

• Standard adult dosage for nutritional supplementation: 16 mg/day for men, 14 mg/day for women, 18 mg/day for pregnant women, 17 mg/day for women who are breastfeeding

• Maximum adult dosage for nutritional supplementation: 35 mg/day

Niacin dosage for high cholesterol and high triglycerides

Nicotinic acid, a chemical version of niacin, is approved by the U.S. Food and Drug Administration (FDA) to reduce “bad” cholesterol (LDL) and fats (triglycerides) while increasing levels of “good” cholesterol (HDL)) in people with hyperlipidemia, atherosclerosis, and severely high triglyceride levels. It is also FDA-approved to prevent heart attacks and other cardiovascular events in individuals with a history of heart disease and high cholesterol. 

Niacin may be prescribed with other cholesterol-lowering drugs like bile acid sequestrants. 

Nicotinic acid is taken at high doses, so side effects are commonly experienced. Niacin causes blood vessels to dilate, so flushing is the most common side effect of taking high doses. Besides skin redness and warmth, niacin flushing can make the face, neck, and shoulders uncomfortably tingly, prickly, or itchy. Nearly everyone will experience flushing when first taking high doses of nicotinic acid. Flushing will improve after a few weeks of treatment, and there are ways to minimize it. Healthcare providers will often prescribe baby aspirin along with high-dose niacin, as the combination helps decrease these side effects. 

• Standard adult dosage for hyperlipidemia: 1000–2000 mg/day taken at bedtime for extended-release tablets or 1000–2000 mg/day taken in three to four divided doses for immediate-release tablets

Niacin dosage for niacin deficiency

Niacin deficiency (called pellagra) rarely occurs in the U.S. However, serious malnutrition, eating disorders, drug abuse, excessive alcohol intake, and digestive system disorders such as malabsorption can result in clinically significant niacin deficiency. 

Once symptoms appear, pellagra is a serious and life-threatening medical condition. The long-term treatment involves adopting a well-balanced diet. In the short term, doctors will prescribe high doses of niacin to reverse the deficiency quickly. Healthcare professionals may use niacin injections in a clinical setting, especially for children. These injections are either given into a muscle or infused intravenously and given four times a day until symptoms resolve.

• Standard adult dosage for niacin deficiency: 250–500 mg/day

Niacin dosage for children

Niacin is used in children as a dietary supplement and a standard treatment for niacin deficiency. However, the use of niacin is not approved as a cholesterol treatment in children. 

• Standard pediatric dosage for niacin supplementation in children from birth to 17 years: See table below

• Standard pediatric dosage for niacin deficiency in children four years of age and older: 300 mg/day intravenous or intramuscular injections spread over doses given four times per day

Source: NIH

Niacin dosage restrictions

Niacin supplements at or below the recommended daily allowance can be taken safely without dosage restrictions. High-dose prescription niacin doesn’t require dosage modifications for people with kidney disease. People with unexplained or sudden liver disease cannot safely take high-dose niacin.

Niacin dosage for pets

Veterinarians may use high-dose niacin with the antibiotic tetracycline in dogs to treat discoid lupus and other inflammatory skin conditions. According to Plumb’s Veterinary Drug Handbook, the standard dosage is 500 mg of niacinamide and 500 mg of tetracycline daily. Symptoms should improve in about six weeks, but dogs will likely experience the side effects of niacin treatment, like flushing and an itchy face.

How to take niacin

Niacin comes in many forms and strengths. Make sure you understand what you’re using, its proper use, and how to use it.

How to take niacin supplements:

• Take niacin supplements as directed by the package instructions or by a healthcare provider. Do not take more than recommended.

• Read the package label for storage instructions.

How to take prescription niacin:

• Follow all the instructions given by the healthcare provider.

• Do not take more than prescribed or take it more frequently than prescribed.

• Do not stop taking prescription niacin unless told to do so. If side effects are difficult, talk to the prescriber before quitting.

• Extended-release niacin should be taken once daily at bedtime unless the prescriber directs otherwise.

• Immediate-release niacin is typically taken in 2–3 doses spread out over the day.

• Swallow niacin capsules or tablets whole. Do not crush, break, or chew them.

• When taking niacin, individuals with high cholesterol should avoid taking bile acid sequestrants, such as cholestyramine or colestipol.

• Prescription niacin tablets may be scored so that they can be broken along the score line to reduce the dose. A healthcare professional will demonstrate how to do this.

• Store prescription niacin tablets or capsules at room temperature.

How to take oral-grade niacinamide powder:

• Follow the directions given on the packaging to prepare a dose.

• Most powders are taken by mixing the powder into food.

• Use caution when measuring a dose—pure niacinamide powder contains large doses (500 mg) in very small measurements (1/5 teaspoon).

• Read the package label for storage instructions. Some powders may require refrigeration or storage in a cool location to maintain their shelf life.

Niacin dosage FAQs

Niacin vs. niacin ER: What’s the difference in doses? 

Niacin ER is not equivalent to immediate-release niacin. Doses will be different and need to be determined by a healthcare professional. Additionally, extended-release niacin is taken once per day at bedtime. Immediate-release niacin is taken in two to three divided doses throughout the day. 

How long does it take niacin to work?

When consumed, the body immediately begins to use niacin. People with a healthy diet will probably not notice any effects. People with niacin deficiency will see symptoms improve after a few days of taking niacin supplements. For cholesterol and lipid treatment, niacin is a long-term treatment. It may take several weeks of niacin therapy to see significant results. 

How long does niacin stay in your system?

Niacin is quickly removed from the body. Its serum half-life is 20 to 40 minutes. 

Niacin supplements and high-dose tablets use different niacin derivatives and come in variable-release formulations. The most common niacin supplements are niacinamide and nicotinic acid. These are processed fairly quickly, but it takes longer to clear a dose of niacinamide (five hours) than nicotinic acid (one hour). 

“No-flush” niacin contains a derivative of niacin called inositol hexanicotinate. The nicotinic acid in the blood peaks in about six to 10 hours after taking a dose. 

Sustained-release and extended-release niacin also take longer to peak and to be eliminated from the body. However, side effects such as flushing are minimized with these formulations because exposure to niacin is spread out.

How long does niacin flushing last?

With immediate-release niacin, flushing typically starts 15 to 30 minutes after taking niacin and lasts 30 minutes to two hours after. When taking niacin ER, the flushing can last one to two and a half hours. 

Fortunately, the body usually adapts in a few weeks of niacin dosing, so this side effect gradually gets more tolerable. Some ways to reduce niacin flushing include:

• Start with low doses and gradually increase them over several weeks.

• Take the niacin tablet with a low-fat snack or meal.

• Avoid alcohol, spicy foods, and hot beverages around the time you take a niacin dose.

• If possible, switch to niacinamide or an extended-release formulation. 

• Flushing can also be prevented by taking aspirin, ibuprofen, or other non-steroidal anti-inflammatory drugs (NSAIDs) about 30–60 minutes before taking a niacin dose.

What happens if I miss a dose of niacin?

If a low-dose niacin supplement is missed, take it when remembered.

If a dose of immediate-release prescription niacin is missed, take it when remembered unless it’s time for the next dose. In that case, take the next dose as scheduled and skip the missed dose.

Prescription niacin ER should only be taken at bedtime. If a dose is missed and it’s the next day, do not take the missed dose. Take that day’s dose at bedtime.

Refrain from taking extra doses to make up for a missed dose.

What is the maximum dosage for niacin?

For niacin supplementation, do not take more than the recommended daily allowance except under the advice of a doctor. The maximum dosage of immediate-release niacin for prescription niacin is six grams daily. The maximum dosage of extended-release niacin is two grams per day.

Can you overdose on niacin?

If you take too much niacin, call a poison helpline or doctor immediately. The typical signs of a niacin overdose include flushing, itching, headache, nausea, and low blood pressure. A severe overdose may cause jaundice or mental changes. 

Sources

• A “hot” topic in dyslipidemia management—“How to beat a flush”: Optimizing niacin tolerability to promote long-term treatment adherence and coronary disease prevention, Mayo Clinic Proceedings

• Niacin, Harvard T.H. Chan School of Public Health

• Niacin, Oregon State University Linus Pauling Institute

• Niacin, StatPearls

• Niacin deficiency, StatPearls

• Niacin fact sheet for consumers, NIH National Institutes of Health

• Niacin fact sheet for health professionals, NIH National Institutes of Health

• Niacin extended-release tablet prescribing information, DailyMed (NIH National Library of Medicine)

• Niacin tablet prescribing information, DailyMed (NIH National Library of Medicine)

• Niacin toxicity, StatPearls

• Niacor niacin tablet prescribing information, DailyMed (NIH National Library of Medicine)

• Niaspan drug summary, Prescriber’s Digital Reference (PDR)

• Pellagra, Cleveland Clinic