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Dietary supplement

Niacinamide 500 mg Ingredients & Drug Interactions

by Douglas Laboratories

Niacinamide 500 mg label
See full label image
Capsule Category: Vitamin
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Niacinamide 500 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Niacinamide 500 mg is a dietary supplement by Douglas Laboratories with 1 active ingredient. Its ingredients are commonly taken for acne and skin health, pellagra (niacin deficiency), anti-aging and skin tone.Based on those ingredients, 124 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Niacinamide. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Niacinamide 500 mg by Douglas Laboratories

Ask about any prescription or over-the-counter medication and we check it for interactions with Niacinamide 500 mg by Douglas Laboratories — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Niacinamide 500 mg by Douglas Laboratories

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Aug 27, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: niacinamide 500 mg per capsule. Niacinamide is a form of vitamin B3 (also called nicotinamide) that your body uses for energy metabolism and DNA repair.

The capsule also holds three inactive ingredients — gelatin, microcrystalline cellulose, and vegetable stearate — which are standard binders and fillers that hold the capsule together and help with absorption.

Does it work?

Strong evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded Niacinamide's overall clinical evidence instead.

Strong

Strong clinical evidence supports Niacinamide for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Pellagra — rated "Likely Effective" (Natural Medicines).
  • On file: Acne — rated "Possibly Effective" (Natural Medicines).
  • On file: Diabetes — rated "Possibly Effective" (Natural Medicines).
  • On file: Osteoarthritis — rated "Possibly Effective" (Natural Medicines).
  • On file: Hyperphosphatemia — rated "Possibly Effective" (Natural Medicines).

Niacinamide is likely effective for pellagra, a serious B3 deficiency disease. The evidence supports its use for acne, high blood phosphate levels (hyperphosphatemia), osteoarthritis, and type 2 diabetes — though for these conditions the evidence is described as possibly effective, meaning more research would strengthen the picture.

For brain tumors, the available evidence suggests it's possibly ineffective.

The evidence, ingredient by ingredient Niacinamide

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Niacinamide at normal dietary levels and standard prenatal-vitamin doses is generally well tolerated and considered likely safe in pregnancy and while breastfeeding. At higher supplemental doses, though, side effects can occur — mostly dizziness, drowsiness, itching, stomach upset, headache, and rash when taken by mouth.

Large doses can trigger nausea, vomiting, heartburn, loss of appetite, and diarrhea. High-dose use should be supervised by a healthcare provider, and pregnant or nursing people should discuss any supplemental dose with their doctor or pharmacist before starting.

When applied to skin, niacinamide can occasionally cause burning, itching, mild skin inflammation, or crusting, though studies suggest the rate of skin side effects is similar to placebo.

Side effects, ingredient by ingredient Niacinamide

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Niacinamide.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 124 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before starting this product, check with your doctor or pharmacist if you take any blood thinners or antiplatelet drugs (especially if you're on hemodialysis), carbamazepine (Tegretol), primidone (Mysoline), or warfarin (Coumadin) — all have documented moderate-severity interactions with niacinamide.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with strong clinical evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

This supplement works well for pellagra and shows promise for acne, joint pain, diabetes, and phosphate management. If you're on a blood thinner, seizure drug, or warfarin, you'll need to check with your doctor or pharmacist before taking it — the interactions are real and worth reviewing with your own medications.

At normal doses it's generally well tolerated, but high doses can upset your stomach and cause other side effects.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jul 23, 2020.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Niacinamide 500 mg, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 310539002896
Net contents 100 Capsule(s)
Market status On market
Date entered into DSLD Jul 23, 2020
DSLD ID 230042
Product type Vitamin
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years), Gluten Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Niacinamide 500 mg by Douglas Laboratories, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
Servings per container
100
UPC/BARCODE
310539002896
IngredientAmount% DV
Niacinamide500 mg2500%

Other ingredients: Gelatin, Microcrystalline Cellulose, Vegetable Stearate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested Usage: As a dietary supplement, adults take 1 capsule daily with food or as directed by your health professional.

Precautions

Warning: If you are pregnant or nursing, or if you are taking prescription medications, consult your health professional before using this supplement.

Keep out of the reach of children.

Use only if safety seal is intact.

Storage

Store in a cool, dry place.

Formulation

Gluten-free, Non-GMO

General Statements

Contents may not fill package in order to accommodate required labeling. Please rely on stated quantity.

Scan to learn about our manufacturing excellence

FDA Statement of Identity

Dietary Supplement

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See for yourself

Niacinamide 500 mg by Douglas Laboratories label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Niacinamide 500 mg label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Niacinamide 500 mg by Douglas Laboratories

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Servings per container100 Amounts shown are per serving.

Niacinamide

Interacts with
124 drugs
500 mg per serving

Niacinamide (also called nicotinamide) is a form of vitamin B3 used in supplements and skin-care products. It is well established for preventing and t...

Niacinamide monograph & interactions

Other (inactive) ingredients: Gelatin, Microcrystalline Cellulose, Vegetable Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Niacinamide 500 mg by Douglas Laboratories Drug Interactions

Want to check YOUR meds against Niacinamide 500 mg?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

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124Drugs
124 Moderate

Ingredients driving the most interactions

Niacinamide 124

Individual Drug Interactions

The ingredients in Niacinamide 500 mg interact with 124 drugs. Click any drug to see the details.

1 of the 1 ingredient in Niacinamide 500 mg interact with drugs. Each result below shows which ingredient is responsible. Niacinamide

Each ingredient & the kinds of drugs it affects

For each ingredient in Niacinamide 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Niacinamide4 drug types · 124 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, niacinamide may have additive effects when used with anticoagulant or antiplatelet drugs, especially in patients on hemodialysis.
Several cases of thrombocytopenia have been reported for hemodialysis patients treated with niacinamide 1 gram daily. Hemodialysis patients receiving niacinamide had almost a three-fold higher risk of developing thrombocytopenia when compared with those receiving placebo.

Likelihood Unlikely Evidence D
Carbamazepine (Tegretol)

Niacinamide might increase the levels and adverse effects of carbamazepine.
Plasma levels of carbamazepine were increased in two children given high-dose niacinamide, 60-80 mg/kg/day. This might be due to inhibition of the cytochrome P450 enzymes involved in carbamazepine metabolism. There is not enough data to determine the clinical significance of this interaction.

Likelihood Possible Evidence D
Primidone (Mysoline)

Niacinamide might increase the levels and adverse effects of primidone.
Case reports in children suggest niacinamide 60-100 mg/kg/day reduces hepatic metabolism of primidone to phenobarbital, and reduces the overall clearance rate of primidone; however, there is not enough data to determine the clinical significance of this potential interaction.

Likelihood Possible Evidence D
Warfarin (Coumadin)

There is limited evidence that niacinamide may increase the anticoagulant effects of warfarin.
In a case report, a patient on warfarin developed an elevated international normalized ratio (INR) of 8.4 after taking niacinamide 500 mg twice daily for 10 days. The patient's INR was previously stable, ranging between 2 and 3, with no other changes to current medications or diet reported. The elevated INR returned to the therapeutic range after receiving vitamin K and discontinuing niacinamide.

Likelihood Possible Evidence D
Niacinamide full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Niacinamide 500 mg, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

Niacinamide 500 mg by Douglas Laboratories: Common Questions

Does Niacinamide 500 mg by Douglas Laboratories interact with any medications?
Yes. Based on its ingredients, Niacinamide 500 mg has a known interaction with 124 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Niacinamide 500 mg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What is niacinamide and what does it do in the body?
Niacinamide is a form of vitamin B3 that helps your cells make energy and repair DNA. It's found naturally in foods like chicken, tuna, and peanuts, and your body needs it to stay healthy.
Is niacinamide safe during pregnancy and while breastfeeding?
Yes — amounts found in food and standard prenatal vitamins are considered safe. If you're thinking about taking a higher supplemental dose, talk with your doctor or pharmacist first to make sure it's right for you.
What side effects can this product cause?
At normal doses, niacinamide is well tolerated. At higher doses, you might notice dizziness, drowsiness, itching, stomach upset, headache, or rash. Large doses can cause nausea, vomiting, heartburn, loss of appetite, and diarrhea.
Does niacinamide actually help with acne?
The evidence suggests it's possibly effective for acne — it shows promise, but more research would help confirm how well it works and for whom.
Why do I need to be careful if I'm on a blood thinner?
Niacinamide may add to the blood-thinning effect of drugs like warfarin and antiplatelet medications, which could raise your bleeding risk. This is especially important in patients on hemodialysis. Your doctor or pharmacist needs to know before you start.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Niacinamide 500 mg label
Go deeper

The Full Monographs Behind Niacinamide 500 mg’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Niacinamide

Interacts with 124 drugs

Niacinamide (also called nicotinamide) is a form of vitamin B3 used in supplements and skin-care products. It is well established for preventing and treating vitamin B3 deficiency, and there...

Read the full Niacinamide monograph →
Sources

Sources & How We Checked

Niacinamide 500 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 22 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Niacinamide 22 references
  1. Pozzilli P, Browne PD, Kolb H. Meta-analysis of nicotinamide treatment in patients with recent-onset IDDM. The Nicotinamide Trialists. Diabetes Care 1996;19:1357-63. PubMed
  2. Greenbaum CJ, Kahn SE, Palmer JP. Nicotinamide's effects on glucose metabolism in subjects at risk for IDDM. Diabetes 1996;45:1631-4. DOI
  3. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. Available at: http://b
  4. Anon. Niacinamide Monograph. Alt Med Rev 2002;7:525-9.
  5. Miralbell R, Mornex F, Greiner R, et al. Accelerated radiotherapy, carbogen, and nicotinamide in glioblastoma multiforme: report of European Organization for Research and Treatment of Cancer trial 22933. J Clin Oncol 1999;17:3143-9. PubMed
  6. Fatigante L, Ducci F, Cartei F, et al. Carbogen and nicotinamide combined with unconventional radiotherapy in glioblastoma multiforme: a new modality treatment. Int J Radiat Oncol Biol Phys 1997;37:499-504. PubMed
  7. Hoskin PJ, Stratford MR, Saunders MI, et al. Administration of nicotinamide during chart: pharmacokinetics, dose escalation, and clinical toxicity. Int J Radiat Oncol Biol Phys 1995;32:1111-9. PubMed
  8. Papa CM. Niacinamide and acanthosis nigricans (letter). Arch Dermatol 1984;120:1281. DOI
  9. Bourgeois BF, Dodson WE, Ferrendelli JA. Interactions between primidone, carbamazepine, and nicotinamide. Neurology 1982;32:1122-6.
  10. Visalli N, Cavallo MG, Signore A, et al. A multi-centre randomized trial of two different doses of nicotinamide in patients with recent-onset type 1 diabetes (the IMDIAB VI). Diabetes Metab Res Rev 1999;15:181-5. DOI
  11. Rottembourg JB, Launay-Vacher V, Massard J. Thrombocytopenia induced by nicotinamide in hemodialysis patients. Kidney Int. 2005;68(6):2911-2. PubMed
  12. Fabbrocini G, Cantelli M, Monfrecola G. Topical nicotinamide for seborrheic dermatitis: an open randomized study. J Dermatolog Treat. 2014 Jun;25(3):241-5. PubMed
  13. Khodaeiani E, Fouladi RF, Amirnia M, Saeidi M, Karimi ER. Topical 4% nicotinamide vs. 1% clindamycin in moderate inflammatory acne vulgaris. Int J Dermatol. 2013 Aug;52(8):999-1004. PubMed
  14. Zhang Y, Ma T, Zhang P. Efficacy and safety of nicotinamide on phosphorus metabolism in hemodialysis patients: A systematic review and meta-analysis. Medicine (Baltimore). 2018;97(41):e12731. PubMed
  15. Ketteler M, Wiecek A, Rosenkranz AR, et al. Efficacy and Safety of a Novel Nicotinamide Modified-Release Formulation in the Treatment of Refractory Hyperphosphatemia in Patients Receiving Hemodialysis-A Randomized Clinical Trial. Kidney Int Rep 2020;6(3): PubMed
  16. Mainville L, Smilga AS, Fortin PR. Effect of Nicotinamide in Skin Cancer and Actinic Keratoses Chemoprophylaxis, and Adverse Effects Related to Nicotinamide: A Systematic Review and Meta-Analysis. J Cutan Med Surg 2022;26(3):297-308. PubMed
  17. Nouh AH, Elshahid AR, Kadah AS, Zeyada YA. Topical niacinamide (Nicotinamide) treatment for discoid lupus erythematosus (DLE): A prospective pilot study. J Cosmet Dermatol 2023.
  18. El-Khalawany M, Nouh AH, Kadah AS, Elsheikh M, Said M. Evaluation of safety and efficacy of topical 4% nicotinamide in treatment of psoriasis; among a representative sample of Egyptians (an analytical observational study). Dermatol Ther 2022;35(9):e15734. PubMed
  19. Zhang H, George-Washburn EA, Hashemi KB, et al. Oral Nicotinamide for Actinic Keratosis Prevention in Kidney Transplant Recipients: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial. Transplant Proc 2023;55(9):2079-2084. PubMed
  20. Oh HJ, Bae SC, Oh IJ, et al. Nicotinamide in Combination with EGFR-TKIs for the Treatment of Stage IV Lung Adenocarcinoma with EGFR Mutations: A Randomized Double-Blind (Phase IIb) Trial. Clin Cancer Res 2024;30(8):1478-1487. PubMed
  21. Schepers L, Jans I, Pot GK, Smilde AJ, Hofstra JM, de Roos NM. The Effect of Niacinamide Supplementation on Phosphate Concentrations in Dutch Dialysis Patients: A Randomized Crossover Trial. J Ren Nutr 2024;34(5):454-462. PubMed
  22. Markham DJ, Barbosa NS, Degesys CA. Elevated International Normalized Ratio After Initiation of Niacin and Niacinamide Chemoprophylaxis for Patients on Warfarin. Dermatol Surg 2024;50(7):690-692. PubMed

See these in context on the Niacinamide monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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