Niacin And Niacinamide (Vitamin B3)

What other names is Niacin known by?

3-Pyridinecarboxylic Acid, Acide Nicotinique, Acide Pyridine-Carboxylique-3, Anti-Blacktongue Factor, Antipellagra Factor, B Complex Vitamin, Complexe de Vitamines B, Facteur Anti-Pellagre, Niacina, Niacine, Nicosedine, Nicotinic Acid, Pellagra Preventing Factor, Vitamin B3, Vitamin PP, Vitamina B3, Vitamine B3, Vitamine PP.

What is Niacin?

Niacin is a form of vitamin B3. It is found in foods such as yeast, meat, fish, milk, eggs, green vegetables, and cereal grains. Niacin is also produced in the body from tryptophan, which is found in protein-containing food. When taken as a supplement, niacin is often found in combination with other B vitamins.

Do not confuse niacin with niacinamide, inositol nicotinate, IP-6, or tryptophan. See the separate listings for these topics.

Niacin is taken by mouth for high cholesterol and other fats. It is also used for low levels of a specific type of cholesterol, HDL. It is also used along with other treatments for circulation problems, migraine headache, Meniere's syndrome and other causes of dizziness, and to reduce the diarrhea associated with cholera. Niacin is also taken by mouth to for preventing positive urine drug screens in people who take illegal drugs.

Niacin is taken by mouth for preventing vitamin B3 deficiency and related conditions such as pellagra. It is also taken by mouth for schizophrenia, hallucinations due to drugs, Alzheimer's disease and age-related loss of thinking skills, chronic brain syndrome, muscle spasms, depression, motion sickness, alcohol dependence, blood vessel swelling linked with skin lesions, and fluid collection (edema).

Some people take niacin by mouth for acne, leprosy, attention deficit-hyperactivity disorder (ADHD), preventing premenstrual headache, improving digestion, protecting against toxins and pollutants, reducing the effects of aging, arthritis, lowering blood pressure, improving circulation, promoting relaxation, improving orgasms, and preventing cataracts. It is also used to improve exercise performance.

Likely Effective for...

  • Abnormal levels of blood fats. Some niacin products are FDA-approved prescription products for treating abnormal levels of blood fats. These prescription niacin products typically come in high strengths of 500 mg or higher. Dietary supplement forms of niacin usually come in strengths of 250 mg or less. Since very high doses of niacin are required for improving cholesterol levels, dietary supplement niacin usually isn't appropriate. For most people who need to lower low-density lipoprotein (LDL or "bad") cholesterol, niacin is considered a second-line therapy. But it may be used as a first line of treatment in people with high levels of both cholesterol AND blood fats called triglycerides. Niacin may be combined with other cholesterol-lowering drugs when diet and single-drug therapy is not enough.
  • Treatment and prevention of niacin deficiency, and certain conditions related to niacin deficiency such as pellagra. Niacin is approved by the U.S. Food and Drug Administration (FDA) for these uses. However, using niacinamide instead of niacin is sometimes preferred because niacinamide doesn't cause "flushing," (redness, itching and tingling), a side effect of niacin treatment.

Possibly Effective for...

  • Hardening of the arteries (atherosclerosis). Taking niacin by mouth along with medicines called bile acid sequestrants seems to reduce hardening of the arteries in men with this condition. It seems to work best in people with high levels of blood fats called triglycerides prior to treatment. Taking niacin with cholesterol-lowering medications also seems to reduce the risk of adverse heart-related adverse events in people with a history of narrowing or hardening of the arteries.
  • Diarrhea from an infection called cholera. Taking niacin by mouth seems to control the loss of fluid due to cholera.
  • Abnormal levels of blood fats in people with HIV/AIDS. Taking niacin seems to improve levels of cholesterol and blood fats called triglycerides in HIV/AIDS patients with abnormal blood fat levels due to antiretroviral treatment.
  • Metabolic syndrome. Taking niacin seems to increase levels of high-density lipoprotein (HDL or "good") cholesterol and reduce levels of blood fats called triglycerides in people with metabolic syndrome. Taking the niacin along with a prescription omega-3 fatty acid seems to work even better.

Insufficient Evidence to Rate Effectiveness for...

  • Alzheimer's disease. People who consume higher amounts of niacin from food and multivitamins seem to have a lower risk of getting Alzheimer's disease than people who consume less niacin. But there is no evidence that taking a stand-alone niacin supplement helps to prevent Alzheimer's disease.
  • Cataracts. Taking niacin by mouth might reduce the risk of nuclear cataracts. Nuclear cataract is the most common type of cataract.
  • Erectile dysfunction. Taking extended-release niacin seems to help men with erectile dysfunction maintain an erection during sexual intercourse.
  • Exercise performance. Research shows that taking a supplement containing niacin and other ingredients before exercise does not improve performance during exercise in men.
  • High levels of phosphate in the blood (hyperphosphatemia). High blood levels of phosphate can result from kidney dysfunction. Some early research shows that taking niacin by mouth can reduce blood levels of phosphate in people with end-stage kidney disease and high levels of blood phosphate. But other research shows that taking niacin by mouth at a higher dose does not lower blood phosphate levels when taken along with medication used to lower blood phosphate levels.
  • Acne.
  • Alcohol dependence.
  • Attention deficit-hyperactivity disorder (ADHD).
  • Depression.
  • Dizziness.
  • Drug-induced hallucinations.
  • Migraine or premenstrual headache.
  • Motion sickness.
  • Schizophrenia.
  • Other conditions.
More evidence is needed to rate niacin for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Quick GuideLower Your Cholesterol, Save Your Heart

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How does Niacin work?

Niacin is absorbed by the body when dissolved in water and taken by mouth. It is converted to niacinamide if taken in amounts greater than what is needed by the body.

Niacin is required for the proper function of fats and sugars in the body and to maintain healthy cells. At high doses, niacin might help people with heart disease because of its beneficial effects on clotting. It may also improve levels of a certain type of fat called triglycerides in the blood.

Niacin deficiency can cause a condition called pellagra, which causes skin irritation, diarrhea, and dementia. Pellagra was common in the early twentieth century, but is less common now, since some foods containing flour are now fortified with niacin. Pellagra has been virtually eliminated in western culture.

People with poor diet, alcoholism, and some types of slow-growing tumors called carcinoid tumors might be at risk for niacin deficiency.

Are there safety concerns?

Niacin is LIKELY SAFE for most people when taken by mouth. A common minor side effect of niacin is a flushing reaction. This might cause burning, tingling, itching, and redness of the face, arms, and chest, as well as headaches. Starting with small doses of niacin and taking 325 mg of aspirin before each dose of niacin will help reduce the flushing reaction. Usually, this reaction goes away as the body gets used to the medication. Alcohol can make the flushing reaction worse. Avoid large amounts of alcohol while taking niacin.

Other minor side effects of niacin are stomach upset, intestinal gas, dizziness, pain in the mouth, and other problems.

When doses of over 3 grams per day of niacin are taken, more serious side effects can happen. These include liver problems, gout, ulcers of the digestive tract, loss of vision, high blood sugar, irregular heartbeat, and other serious problems.

Some concern has been raised about stroke risk in people taking niacin. In one large study, people who took high doses of niacin had a two-fold greater risk of stroke compared to those not taking niacin. However, it is unlikely that this outcome was due to niacin. Most experts believe that it is too soon to draw any conclusions about niacin and strokes.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Niacin is LIKELY SAFE for pregnant and breast-feeding women when taken in the recommended amounts. The recommended amount of niacin for pregnant or breast-feeding women is 30 mg per day for women under 18 years of age, and 35 mg for women over 18.

Allergies: Niacin might worsen allergies by causing histamine, the chemical responsible for allergic symptoms, to be released.

Heart disease/unstable angina: Large amounts of niacin can increase the risk of irregular heartbeat. Use with caution.

Crohn's disease: People with Crohn's disease might have low niacin levels and require supplementation during flare-ups.

Diabetes: Niacin might increase blood sugar. People with diabetes who take niacin should check their blood sugar carefully.

Gallbladder disease: Niacin might make gallbladder disease worse.

Gout: Large amounts of niacin might bring on gout.

Kidney disease: Niacin might accumulate in people with kidney disease. This might cause harm.

Liver disease: Niacin might increase liver damage. Don't use large amounts if you have liver disease.

Stomach or intestinal ulcers: Niacin might make ulcers worse. Don't use large amounts if you have ulcers.

Very low blood pressure: Niacin might lower blood pressure and worsen this condition.

Surgery: Niacin might interfere with blood sugar control during and after surgery. Stop taking niacin at least 2 weeks before a scheduled surgery.

Fatty deposits around tendons (tendon xanthomas): Niacin might increase the risk of infections in xanthomas.

Thyroid disorders: Thyroxine is a hormone produced by the thyroid gland. Niacin might lower blood levels of thyroxine. This might worsen symptoms of certain thyroid disorders.

Are there any interactions with medications?



Alcohol (Ethanol)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Niacin can cause flushing and itchiness. Consuming alcohol along with niacin might make the flushing and itching worse. There is also some concern that consuming alcohol with niacin might increase the chance of having liver damage.



Allopurinol (Zyloprim)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Allopurinol (Zyloprim) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of allopurinol (Zyloprim).



Clonidine (Catapres)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Clonidine and niacin both lower blood pressure. Taking niacin with clonidine might cause your blood pressure to become too low.



Gemfibrozil (Lopid)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Taking niacin along with gemfibrozil might cause muscle damage in some people. Use with caution.



Medications for diabetes (Antidiabetes drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Use of high doses of niacin (about 3-4 grams daily) might increase blood sugar. By increasing blood sugar, niacin might decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), metformin (Glucophage), nateglinide (Starlix), repaglinide (Prandin), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.



Medications for high blood pressure (Antihypertensive drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Using niacin with drugs that lower blood pressure may increase the effects of these drugs and may lower blood pressure too much.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), amlodipine (Norvasc), hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.



Medications that can harm the liver (Hepatotoxic drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Niacin might harm the liver. Sustained-release niacin preparations seem to have the greatest risk. Taking niacin along with medication that might also harm the liver can increase the risk of liver damage. Do not take niacin if you are taking a medication that can harm the liver.

Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.



Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Niacin might slow blood clotting. Taking niacin along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, indomethacin (Indocin), ticlopidine (Ticlid), warfarin (Coumadin), and others.



Medications used for lowering cholesterol (Bile acid sequestrants)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications for lowering cholesterol called bile acid sequestrants can decrease how much niacin the body absorbs. This might reduce the effectiveness of niacin. Take niacin and the medications at least 4-6 hours apart.

Some of these medications used for lowering cholesterol include cholestyramine (Questran) and colestipol (Colestid).



Medications used for lowering cholesterol (Statins)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Niacin can adversely affect the muscles. Some medications used for lowering cholesterol called statins can also affect the muscles. Taking niacin along with these medications might increase the risk of muscle problems.

Some of these medications used for high cholesterol include rosuvastatin (Crestor), atorvastatin (Lipitor), lovastatin (Mevacor), pravastatin (Pravachol), fluvastatin (Lescol), and simvastatin (Zocor).



Probenecid
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Probenecid is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of probenecid.



Sulfinpyrazone (Anturane)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Sulfinpyrazone (Anturane) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of sulfinpyrazone (Anturane).



Thyroid hormone
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body naturally produces thyroid hormones. Niacin might decrease thyroid hormone levels. Taking niacin with thyroid hormone pills might decrease the effects and side effects of thyroid hormone.



Aspirin
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

Aspirin is often used with niacin to reduce the flushing caused by niacin. Taking high doses of aspirin might decrease how fast the body gets rid of niacin. This could cause there to be too much niacin in the body and possibly lead to side effects. However, the low doses of aspirin most commonly used for niacin-related flushing don't seem to be a problem.



Nicotine patch (Transdermal nicotine)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

Niacin can sometimes cause flushing and dizziness. The nicotine patch can also cause flushing and dizziness. Taking niacin or niacinamide and using a nicotine patch can increase the possibility of becoming flushed and dizzy.

Dosing considerations for Niacin.

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:
  • For high cholesterol: The effects of niacin are dose-dependent. Doses of niacin have been as low as 50 mg and as high as 12 grams each day have been used. However,But tThe most common doses are between 1-3 grams daily.biggest increases in HDL and decreases in triglycerides occur at 1200-1500 mg/day. Niacin's greatest effects on LDL occur at 2000-3000 mg/day. Niacin may be is often used with other medications for improving cholesterol levels.
  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 300-1000 mg daily in divided doses.
  • For treating hardening of the arteries: Doses of niacin have been as high as 12 grams daily. However, dose of about 1000-4200 mg1-4 grams of niacin daily, alone or along with statins or bile acid sequestrantscholesterol-lowering medicine, has beenis most commonly used for up to 6.2 years.
  • For reducing fluid loss caused by cholera toxin: 2 grams daily has been used.
  • For abnormal blood fat levels due to treatment for HIV/AIDS: Up to 2 grams daily has been used.
  • For metabolic syndrome: 2 grams of niacin has been taken daily for 16 weeks. In some cases it is taken Niacin 2 grams daily, alone or at this dosage along with 4 grams of prescription omega-3 ethyl esters (Lovaza, GlaxoSmithKline Pharmaceuticals)
BY IV:
  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 60 mg of niacin has been used.
AS A SHOT:
  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 60 mg of niacin has been used.
CHILDREN

BY MOUTH:
  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 100-300 mg per day of niacin, given in divided doses.
The daily recommended dietary allowances (RDAs) of niacin are: Infants 0-6 months, 2 mg; Infants 7-12 months, 4 mg; Children 1-3 years, 6 mg; Children 4-8 years, 8 mg; Children 9-13 years, 12 mg; Men 14 years and older, 16 mg; Women 14 years and older, 14 mg; Pregnant women, 18 mg; and Lactating women, 17 mg. The tolerable upper level (UL) for maximum daily dose of niacin is: Children 1-3 years, 10 mg; Children 4-8 years, 15 mg; Children 9-13 years, 20 mg; Adults, including Pregnant and Lactating women, 14-18 years, 30 mg; and Adults, including pregnant and breast-feeding women, older than 18 years, 35 mg.

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Last Editorial Review: 3/29/2011

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