Niacin (Vitamin B3, Nicotinic acid), Niacinamide Dosing and Safety

safety

Allergies

Avoid in people with known allergy or sensitivity to niacin, niacinamide, or products containing one or both of these products.
Rarely, anaphylactic shock (severe allergic reaction) has been described after giving niacin by mouth or injecting it into the vein.

Side Effects and Warnings

Niacin is likely safe when taken by mouth daily in recommended amounts under the supervision of a qualified healthcare provider. Homocysteine levels should be monitored.
Niacin or niacinamide may result in the following side effects: abnormal heart rhythms, ascites (fluid build-up in the gut lining), blurred vision, build-up of lactic acid in the body, bleeding disorders, changes in liver structure, changes in thyroid hormones, decreased platelets, decreased fibrinogen (chemical that helps clotting), decreased white blood cells, diarrhea, displacement of the eye, dizziness, dry eyes, dry skin, eye disease, eye swelling, eyebrow and eyelash discoloration, failure of blood circulation, fainting, flushing, headache, heartburn, hernia, hypothyroidism (under-active thyroid), increased blood volume in the eye, increased heartbeat, increased creatine kinase, increased homocysteine levels, increased insulin resistance, increased insulin in the blood, increased liver enzymes, increased risk of muscle breakdown, increased uric acid levels in the blood, increased eosinophils (a white blood cell), inflammation of the cornea of the eye, insulin resistance, itching, jaundice (yellowing of the skin), liver adverse effects, liver damage, liver inflammation, liver failure, loss of eyebrows and eyelashes, migraine, muscle disease, nausea, pain in the gums and teeth, panic, peptic ulcer disease, rash, stomach upset, sugar and ketones in the urine, swelling, vision loss due to toxic reactions, vomiting, and warm sensations.
Niacin may increase blood sugar levels. Caution is advised in people with diabetes who are not monitored by a qualified healthcare provider and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
Niacin may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
Use cautiously in people with kidney disorders and gout.
Use cautiously in children.
Avoid in people with sensitivity to niacin, niacinamide, or products containing one or both of these products.
Avoid in people with liver dysfunction or disease, peptic ulcer disease, or arterial bleeding.

Pregnancy and Breastfeeding

There is a lack of research regarding the use of niacin during pregnancy and breastfeeding.

dosing

Adults (over 18 years old)

The dietary reference intake established by the Food and Nutrition Board for niacin ranges from 14-18 milligrams niacin daily by mouth for adults, with an upper intake level of 35 milligrams daily by mouth. Niacinamide and niacin are used in cosmetics, as well as hair and skin products. The concentration of niacinamide varies from a low of 0.0001% in night preparations to a high of 3% in body and hand creams, lotions, powders, and sprays. Niacin concentrations range from 0.01% in body and hand creams, lotions, powders, and sprays to 0.1% in paste masks (mud packs).
For age-related macular disease (eye disease), 500 milligrams of immediate-release niacin has been taken by mouth.
For preventing clogged arteries, 3,000-4,000 milligrams of niacin has been taken by mouth daily alone or in combination with other cholesterol therapy for 0.5-6.2 years.
For heart disease, 0.125-12 grams of niacin has been taken by mouth daily for up to five years.
For erectile dysfunction, 500-1,500 milligrams of niacin (Niaspan®) has been taken by mouth for 12 weeks.
For high cholesterol, 300-1,2000 milligrams of niacin has been taken by mouth daily for 6-44 weeks as wax-matrix, immediate-release (crystalline); 2 grams of niacin has been injected into the vein over 11 hours. The maximum recommended daily dose is 3 grams.
For high cholesterol (in combination with statins or bile acid sequestrants) 500-4,000 milligrams of extended-release or regular niacin has been taken by mouth daily for eight weeks to 6.2 years. Extended-or sustained-release niacin may be started at a dose of 500 milligrams daily and titrated up to 3 grams daily.
For high cholesterol levels in HIV-infected patients 500-2,000 milligrams of extended-release niacin (Niaspan®) has been taken by mouth daily for 44 weeks to two years.
For high blood phosphorous levels, a single 375 milligram dose of extended-release nicotinic acid has been taken by mouth.
For osteoarthritis, 3 grams of niacinamide has been taken by mouth daily for 12 weeks.
For pellagra, or niacin deficiency, 50-1,000 milligrams of niacin has been taken by mouth daily.
For skin conditions, 2-5% of niacinamide cream has been applied to the skin for up to 12 weeks.
For type 1 diabetes mellitus prevention, 200-3,000 milligrams of niacinamide has been taken by mouth daily for up to one year; 20-40 milligrams per kilogram of niacinamide has been taken daily by mouth for up to one year and lacked evidence of benefit.
For type 2 diabetes, 0.5 grams of nicotinamide has been taken by mouth three times daily for six months.

Children (under 18 years old)

There is no proven safe or effective dose for niacin in children.
For type 1 diabetes mellitus prevention, 200-3,000 milligrams of niacinamide has been taken by mouth daily for up to one year; 20-40 milligrams per kilogram has been taken by mouth daily for up to five years, and lacked evidence of benefit.

interactions

Interactions with Drugs

Niacin may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
Niacin may increase blood sugar levels. Caution is advised when using medications that may alter blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Niacin may cause low blood pressure. Caution is advised in people taking drugs that lower blood pressure.
Niacin may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be altered in the blood, and may cause altered effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
Niacin may also interact with agents for the heart, agents that widen blood vessels, agents used for the liver, agents used for seizures, alcohol, androgens, antibiotics, antigout agents, antihistamines, antithyroid agents, aspirin, benzodiazepines, birth control taken by mouth, calcium-channel blockers, cholesterol-lowering agents (bile acid sequestrants, fibrates, HMG-CoA reductase inhibitors), epinephrine, estrogens, ganglionic blocking drugs, griseofulvin, neomycin, nicotine, nonsteroidal anti-inflammatory drugs (NSAIDs), primidone, probucol, procetofene, progestins, pyrazinamide, theophylline, and thyroid hormones.

Interactions with Herbs and Dietary Supplements

Niacin may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
Niacin may increase blood sugar levels. Caution is advised when using herbs or supplements that may alter blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
Niacin may cause low blood pressure. Caution is advised in people taking herbs or supplements that lower blood pressure.
Niacin may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may be altered in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
Niacin may also interact with amino acids, androgens, antibacterials, antigout herbs and supplements, antihistamines, antioxidants, antithyroid herbs and supplements, cholesterol-lowering herbs and supplements, chromium, coffee, ganglionic blocking herbs and supplements, grape seed, herbs and supplements for the heart, herbs and supplements that widen blood vessels, herbs and supplements used for the liver, herbs and supplements used for birth control, herbs and supplements used for seizures, inositol hexanicotinate, kava, minerals, pantothenic acid, phytoestrogens, phytoprogestins, salicylate-containing herbs, sitosterols, sorghum, thyroid hormones, tryptophan, vitamins E, A, and B6, and zinc sulfate.