Major interaction on record — check this product against your medications before combining. Check your meds →
Dietary supplement

Niacinamide 500 mg Ingredients & Drug Interactions

by 21st Century

Niacinamide 500 mg label
See full label image
Tablet Or Pill Category: Single Vitamin And Mineral
Most serious interaction: Major
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: Major

Niacinamide 500 mg is a dietary supplement by 21st Century with 2 active ingredients. Its ingredients are commonly taken for bone health and osteoporosis prevention, dietary calcium deficiency, heartburn relief (calcium carbonate antacids).Based on those ingredients, 287 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Calcium, Niacinamide. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Niacinamide 500 mg by 21st Century

Ask about any prescription or over-the-counter medication and we check it for interactions with Niacinamide 500 mg by 21st Century — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of Niacinamide 500 mg by 21st Century

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 Jul 11, 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 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This tablet contains two active ingredients: niacinamide 500 mg and calcium. Niacinamide is a form of vitamin B3 that your body needs to turn food into energy and maintain healthy skin and nerve function.

Calcium is a mineral essential for bone strength, muscle function, and heart rhythm. The product also contains several inactive ingredients — cellulose, hydroxypropyl methylcellulose, stearic acid, gum acacia, magnesium silicate, magnesium stearate, polyethylene glycol, polysorbate, polyvinyl alcohol, and silicon dioxide — which are fillers and binders that help form the tablet.

Does it work?

Not established
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
Not established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use.

Why this rating?
  • The label markets this product for: Energy and circulatory support.
  • We looked for evidence on: Cardiovascular disease (CVD), Dyslipidemia, Atherosclerosis, Heart failure, Myocardial infarction (MI), Stroke — and 2 related terms.
  • The closest evidence on file: Calcium is rated "Ineffective" for Cardiovascular disease (CVD) (Natural Medicines).
  • Also on file: Calcium is rated "Ineffective" for Myocardial infarction (MI).
  • Also on file: Calcium is rated "Insufficient Reliable Evidence To Rate" for Atherosclerosis, Heart failure, Dyslipidemia, Stroke.

The evidence for calcium in this product is strong: it's effective for preventing low blood calcium (hypocemia), managing high potassium (hyperkalemia), treating indigestion (dyspepsia), helping kidney failure patients, and is likely effective for osteoporosis. Niacinamide is likely effective for pellagra (a vitamin B3 deficiency disease) and possibly effective for acne, high blood phosphate (hyperphosphatemia), osteoarthritis, and diabetes, though the evidence for those last few is more limited.

For brain tumors, the evidence actually suggests niacinamide is likely ineffective.

The evidence, ingredient by ingredient Calcium 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 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Calcium is generally well tolerated at recommended doses, though high amounts can cause problems. The most common side effects are belching, constipation, diarrhea, gas, and stomach upset.

Serious effects are rare but have included kidney stones and a skin condition called calciphylaxis. There's also some concern that very high calcium intake—over 1,500 to 2,000 mg daily—might slightly increase prostate cancer risk and possibly cardiovascular risk, though research on this is mixed.

Niacinamide at standard doses is usually well tolerated, but high doses can cause dizziness, drowsiness, itching, headache, rash, and stomach problems including nausea, vomiting, and heartburn. For pregnancy, adequate calcium is important and standard amounts are considered likely safe, though the data also notes one rating of possibly unsafe—discuss your individual needs with your doctor.

Niacinamide at dietary and prenatal-vitamin amounts is likely safe in pregnancy; high doses should be discussed with your provider. For breastfeeding, both ingredients at recommended amounts are considered acceptable.

Side effects, ingredient by ingredient Calcium Niacinamide

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 2 of the 2 matched ingredients can interact with medications — Calcium, Niacinamide.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; heart-rhythm medications; lithium.
  • For scale: 287 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 you take this product, double-check with your pharmacist if you're on HIV medications (dolutegravir, elvitegravir, raltegravir), the antibiotic ceftriaxone (especially intravenously), thyroid medication (levothyroxine), blood thinners (warfarin or other anticoagulants), seizure drugs (carbamazepine, primidone), heart medications (sotalol, diltiazem), or the psoriasis treatment calcipotriene. Calcium and niacinamide can affect how these drugs work.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Major medication interactions have been identified, and safety information is well characterized.

This product makes sense if you need both a calcium supplement and niacinamide — for example, if you're at risk for osteoporosis and your doctor has recommended B3 supplementation. But if you take blood thinners, HIV medications, thyroid medicine, seizure drugs, or heart medications, you need to check your specific prescriptions with your pharmacist first.

Anyone on prescription medications should verify their list before starting.

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

Assessment coverage: 2 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Mar 25, 2025.

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 21st Century
Barcode (UPC) 740985225509
Net contents 110 Tablet(s)
Market status On market
Date entered into DSLD Mar 25, 2025
DSLD ID 326336
Product type Single Vitamin And Mineral
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Gluten Free, Dairy 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 21st Century, 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 Tablet(s)
Maximum serving Sizes:
1 Tablet(s)
Servings per container
110
UPC/BARCODE
740985225509
IngredientAmount% DV
Calcium160 mg12%
Niacinamide500 mg3125%

Other ingredients: Cellulose, Hydroxypropyl Methylcellulose, Stearic Acid, Gum Acacia, Magnesium Silicate, Magnesium Stearate, Polyethylene Glycol, Polysorbate, Polyvinyl Alcohol, Silicon Dioxide

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

Directions: As a vitamin supplement, adults take one (1) tablet daily with any meal or as directed by a healthcare provider.

Precautions

Do not exceed recommended dosage. Individual results may vary. Stop use and contact a physician if adverse reactions occur. Do not use if product appears to be tampered with or seal is broken.

Warning: Consult a healthcare provider prior to use if pregnant, nursing, on medications, have a medical condition or are planning a medical procedure.

Keep out of reach of children.

Storage

Store at room temperature.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Formulation

Prolonged release Energy & circulatory support Prolonged release vitamins slowly release nutrients into the body over an extended period of time.

Gluten free Non-GMO

No added sugar, salt, yeast, preservatives, artificial flavors or colors.

Suitable for vegans.

Guaranteed quality Laboratory tested Trusted Quality For Over 30 Years

FDA Statement of Identity

Vitamin Supplement

Formula

Niacin (Vitamin B-3) plays a role in energy metabolism. Niacinamide is a good source of Vitamin B-3 with a lower flushing effect than that of niacin.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Niacinamide 500 mg by 21st Century 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 21st Century

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Tablet(s) Dosage formTablet Or Pill Servings per container110 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Calcium

Interacts with
168 drugs
160 mg per serving Form: Calcium Carbonate

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet f...

Calcium monograph & interactions

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: Cellulose, Hydroxypropyl Methylcellulose, Stearic Acid, Gum Acacia, Magnesium Silicate, Magnesium Stearate, Polyethylene Glycol, Polysorbate, Polyvinyl Alcohol, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Niacinamide 500 mg by 21st Century 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.

 Go to the checker
287Drugs
7 Major 262 Moderate 18 Minor

Ingredients driving the most interactions

Calcium 168
Niacinamide 124

Individual Drug Interactions

The ingredients in Niacinamide 500 mg interact with 287 drugs. Click any drug to see the details.

2 of the 2 ingredients in Niacinamide 500 mg interact with drugs. Each result below shows which ingredient is responsible. Calcium 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 they can affect. Open any type for the detail — or search your exact drug in the checker above.

Calcium18 drug types · 168 drugs

Ceftriaxone (Rocephin)

Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.
Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction. So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

Likelihood Probable Evidence D
Dolutegravir (Tivicay)

Calcium seems to reduce levels of dolutegravir.
Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation.

Likelihood Probable Evidence B
Elvitegravir (Vitekta)

Calcium seems to reduce levels of elvitegravir.
Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation.

Likelihood Probable Evidence B
Aluminum

Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.
Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease. However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption.

Likelihood Possible Evidence B
Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy)

Calcium might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Advise patients that bictegravir/emtricitabine/tenofovir alafenamide and calcium can be taken together if taken with food. However, if taken on an empty stomach, bictegravir/emtricitabine/tenofovir alafenamide should not be taken with, or 2 hours after, calcium containing products.

Likelihood Probable Evidence D
Bisphosphonates

Calcium reduces the absorption of bisphosphonates.
Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates.

Likelihood Probable Evidence C
Calcipotriene (Dovonex)

Taking calcipotriene with calcium might increase the risk for hypercalcemia.
Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia. Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

Likelihood Possible Evidence B
Digoxin (Lanoxin)

Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.
Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin. However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin.

Likelihood Possible Evidence B
Diltiazem (Cardizem, Others)

Theoretically, calcium may reduce the therapeutic effects of diltiazem.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

Likelihood Probable Evidence D
Levothyroxine (Synthroid, Others)

Calcium seems to reduce the absorption and effectiveness of levothyroxine.
Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes. Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism.

Likelihood Probable Evidence B
Lithium

Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.
Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients. Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

Likelihood Possible Evidence B
Quinolone Antibiotics

Calcium seems to reduce the absorption of quinolone antibiotics.
Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut.

Likelihood Probable Evidence B
Raltegravir (Isentress)

Calcium may reduce levels of raltegravir.
Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir. However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure.

Likelihood Possible Evidence B
Sotalol (Betapace)

Calcium seems to reduce the absorption of sotalol.
Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes.

Likelihood Possible Evidence B
Tetracycline Antibiotics

Calcium seems to reduce the absorption of tetracycline antibiotics.
Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut.

Likelihood Probable Evidence C
Thiazide Diuretics

Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Thiazides reduce calcium excretion by the kidneys. Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

Likelihood Probable Evidence C
Verapamil (Calan, Others)

Theoretically, calcium may reduce the therapeutic effects of verapamil.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

Likelihood Probable Evidence D
Calcium Channel Blockers

Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects. But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers.

Likelihood Unlikely Evidence D
Calcium full monograph & interactions

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.

21st Century

See all 21st Century products
Name
21st Century HealthCare, Inc.
Street Address
2119 S. Wilson St.
City
Tempe
State
AZ
ZipCode
85282
Web Address
21stcenturyvitamins.com
Pharmacist Counseling Corner

Niacinamide 500 mg by 21st Century: Common Questions

Does Niacinamide 500 mg by 21st Century interact with any medications?
Yes. Based on its ingredients, Niacinamide 500 mg has a known interaction with 287 medications, including 7 rated major. 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 2 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is 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.
Will this help my bones?
The calcium in this product is likely effective for osteoporosis. But you'll get the most benefit if you're also getting enough vitamin D and doing weight-bearing exercise — talk to your doctor about your full bone-health plan.
Can I take this if I'm pregnant?
Adequate calcium is important in pregnancy, and standard amounts are considered likely safe. However, niacinamide at high supplemental doses should be discussed with your doctor first — dietary amounts and those in prenatal vitamins are fine. Check with your provider about what's right for you.
What side effects might I notice?
The most common are constipation, gas, and stomach upset from the calcium, or dizziness, drowsiness, and headache from the niacinamide. High doses of either can cause more serious stomach problems. If you experience ongoing side effects, let your pharmacist know.
Is niacinamide the same as niacin?
No — niacinamide and niacin are both forms of vitamin B3, but niacinamide doesn't cause the 'flushing' (hot, red skin) that niacin does. This product has niacinamide, so you're less likely to experience that side effect.
How far apart should I space this from my levothyroxine?
If you take levothyroxine (Synthroid), take it and this calcium supplement at least 4 hours apart — calcium can reduce how well your thyroid medicine is absorbed. Your pharmacist can help you plan a dosing schedule that works.
Can I take this if I'm on warfarin?
The niacinamide in this product may increase warfarin's effect and raise your bleeding risk, especially at high doses. You'll need your doctor or pharmacist to review this with you and possibly monitor your blood-clotting time more closely.

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

Not sure if Niacinamide 500 mg is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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

Calcium

Interacts with 168 drugs

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet falls short. Most people do best getting...

Read the full Calcium monograph → 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 84 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.

Calcium 62 references
  1. Shils M, Olson A, Shike M. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, PA: Lea and Febiger, 1994.
  2. Hernandez-Avila M, Gonzalez-Cossio T, Hernandez-Avila JE, et al. Dietary calcium supplements to lower blood lead levels in lactating women: a randomized placebo-controlled trial. Epidemiology 2003;14:206-12.. PubMed
  3. Thys-Jacobs S, Ceccarelli S, Bierman A, et al. Calcium supplementation in premenstrual syndrome: a randomized crossover trial. J Gen Intern Med 1989;4:183-9. PubMed
  4. Maton PN, Burton ME. Antacids revisited: a review of their clinical pharmacology and recommended therapeutic use. Drugs 1999;57:855-70.
  5. Clemens JD, Feinstein AR. Calcium carbonate and constipation: a historical review of medical mythopoeia. Gastroenterology 1977;72:957-61. DOI
  6. Saunders D, Sillery J, Chapman R. Effect of calcium carbonate and aluminum hydroxide on human intestinal function. Dig Dis Sci 1988;33:409-13. PubMed
  7. Friedman PA, Bushinsky DA. Diuretic effects on calcium metabolism. Semin Nephrol 1999;19:551-6.
  8. Koo WK, Walters JC, Esterlitz J, et al. Maternal calcium supplementation and fetal bone mineralization. Obstet Gynecol 1999;94:577-82. DOI
  9. Raman L, Rajalakshmi K, Krishnamachari KAVR, et al. Effect of calcium supplementation to undernourished mothers during pregnancy on the bone density of the neonates. Am J Clin Nutr 1978; 31:466-9. DOI
  10. Murry JJ, Healy MD. Drug-mineral interactions: a new responsibility for the hospital dietician. J Am Diet Assoc 1991;91:66-73.
  11. Chan JM, Giovannucci E, Andersson SO, et al. Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer. Cancer Causes Control 1998;9:559-66.
  12. Butner LE, Fulco PP, Feldman G, et al. Calcium carbonate-induced hypothyroidism. Ann Intern Med 2000:132:595. PubMed
  13. Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. JAMA 1998;279:750. PubMed
  14. Moser LR, Smythe MA, Tisdale JE. The use of calcium salts in the prevention and management of verapamil-induced hypotension. Ann Pharmacother 2000;34:622-9. PubMed
  15. Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA 2000;283:2822-5. PubMed
  16. Kahela P, Anttila M, Tikkanen R, Sundquist H. Effect of food, food constituents and fluid volume on the bioavailability of sotalol. Acta Pharmacol Toxicol (Copenh) 1979;44:7-12.. PubMed
  17. Pletz MW, Petzold P, Allen A, et al. Effect of calcium carbonate on bioavailability of orally administered gemifloxacin. Antimicrob Agents Chemother 2003;47:2158-60.. PubMed
  18. Bar-Or D, Yoel G. Calcium and calciferol antagonize effect of verapamil in atrial fibrillation. Br Med J 1981;282:1585-6.
  19. Decktor DL, Robinson M, Maton PN, et al. Effects of aluminum/magnesium hydroxide and calcium carbonate on esophageal and gastric pH in subjects with heartburn. Am J Ther 1995;2:546-52. PubMed
  20. Simoneau G. Absence of rebound effect with calcium carbonate. Eur J Drug Metab Pharmacokinet 1996;21:351-7. PubMed
  21. Peters ML, Leonard M, Licata AA. Role of alendronate and risedronate in preventing and treating osteoporosis. Cleve Clin J Med 2001;68:945-51. PubMed
  22. Bourke JF, Mumford R, Whittaker P, et al. The effects of topical calcipotriol on systemic calcium homeostasis in patients with chronic plaque psoriasis. J Am Acad Dermatol 1997;37:929-34.
  23. Gueguen L, Pointillart A. The bioavailability of dietary calcium. J Am Coll Nutr 2000;19:119s-136s. PubMed
  24. Vella A, Gerber TC, Hayes DL, Reeder GS. Digoxin, hypercalcaemia, and cardiac conduction. Postgrad Med J 1999;75:554-6. PubMed
  25. Bania TC, Blaufeux B, Hughes S, et al. Calcium and digoxin vs. calcium alone for severe verapamil toxicity. Acad Emerg Med 2000;7:1089-96. PubMed
  26. Tseng M, Breslow RA, Graubard BI, Ziegler RG. Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort. Am J Clin Nutr 2005;81:1147-54. PubMed
  27. Weingarten MA, Zalmanovici A, Yaphe J. Dietary calcium supplementation for preventing colorectal cancer and adenomatous polyps. Cochrane Database Syst Rev 2004;(1):CD003548. PubMed
  28. Tavani A, Bertuccio P, Bosetti C, et al. Dietary intake of calcium, vitamin D, phosphorus and the risk of prostate cancer. Eur Urol 2005;48:27-33. PubMed
  29. Giovannucci E, Liu Y, Stampfer MJ, Willett WC. A prospective study of calcium intake and incident and fatal prostate cancer. Cancer Epidemiol Biomarkers Prev 2006;15:203-10. PubMed
  30. Rocephin (ceftriaxone) and calcium interaction. Pharmacist's Letter / Prescriber's Letter 2007;23(10):231005.
  31. Bolland MJ, Barber PA, Doughty RN, et al. Vascular events in healthy older women receiving calcium supplementation: randomised control trial. BMJ 2008;336:262-6.
  32. Bolland MJ, Avenell A, Baron JA, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010;341:c3691. PubMed
  33. Calcium supplementation and vascular events. Pharmacist's Letter / Prescriber's Letter 2008;24(3):240306.
  34. Dietary reference intakes for calcium and vitamin D. Institute of Medicine, November 30, 2010. Available at: http://www.iom.edu/~/media/Files/Report%20Files/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Vitamin%20D%20and%20Calcium%202010%20Repo
  35. Coburn JW, Mischel MG, Goodman WG, et al. Calcium citrate markedly enhances aluminum absorption from aluminum hydroxide. Am J Kidney Dis. 1991;17(6):708-11. PubMed
  36. Bradley JS, Wassel RT, Lee L, et al. Intravenous ceftriaxone and calcium in the neonate: assessing the risk for cardiopulmonary adverse events. Pediatrics. 2009;123(4):e609-13. PubMed
  37. Kays MB, Overholser BR, Mueller BA, et al. Effects of sevelamer hydrochloride and calcium acetate on the oral bioavailability of ciprofloxacin. Am J Kidney Dis. 2003;42(6):1253-9. PubMed
  38. Neuhofel, A. L., Wilton, J. H., Victory, J. M., Hejmanowsk, L. G., and Amsden, G. W. Lack of bioequivalence of ciprofloxacin when administered with calcium-fortified orange juice: a new twist on an old interaction. J Clin Pharmacol. 2002;42(4):461-466. DOI
  39. Dickinson, H. O., Nicolson, D. J., Cook, J. V., Campbell, F., Beyer, F. R., Ford, G. A., and Mason, J. Calcium supplementation for the management of primary hypertension in adults. Cochrane.Database.Syst.Rev. 2006;(2):CD004639. PubMed
  40. Jones, B. J. and Twomey, P. J. Requesting patterns for serum calcium concentration in patients on long-term lithium therapy. Int J Clin Pract. 2009;63(1):170-172. PubMed
  41. Levine, M., Nikkanen, H., and Pallin, D. J. The effects of intravenous calcium in patients with digoxin toxicity. J Emerg.Med. 2011;40(1):41-46. PubMed
  42. Castelo-Branco, C., Ciria-Recasens, M., Cancelo-Hidalgo, M. J., Palacios, S., Haya-Palazuelos, J., Carbonell-Abello, J., Blanch-Rubio, J., Martinez-Zapata, M. J., Manasanch, J., and Perez-Edo, L. Efficacy of ossein-hydroxyapatite complex compared with ca
  43. Li K, Kaaks R, Linseisen J, Rohrmann S. Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation i
  44. Chung M, Tang AM, Fu Z. Calcium Intake and Cardiovascular Disease Risk: An Updated Systematic Review and Meta-analysis. Ann Intern Med. 2016 Oct 25. PubMed
  45. Nolan CR, Califano JR, Butzin CA. Influence of calcium acetate or calcium citrate on intestinal aluminum absorption. Kidney Int. 1990;38(5):937-41. PubMed
  46. Lewis JR, Radavelli-Bagatini S, Rejnmark L, et al. The effects of calcium supplementation on verified coronary heart disease hospitalization and death in postmenopausal women: a collaborative meta-analysis of randomized controlled trials. J Bone Miner Res PubMed
  47. Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
  48. Lappe J, Watson P, Travers-Gustafson D, Recker R, Garland C, Gorham E, Baggerly K, McDonnell SL. Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial. JAMA. 2017 Mar 28;317(12):1234-1243. PubMed
  49. Grove ML, Cook D. Calcium and heart attacks. Doesn't apply to most calcium prescriptions. BMJ. 2010;341:c5003. PubMed
  50. Insentress [package insert]. Whitehouse Station, NJ: Merck Sharp & Dohme Corp.; 2014.
  51. Roberts JL, Kiser JJ, Hindman JT, Meditz AL. Virologic failure with a raltegravir-containing antiretroviral regimen and concomitant calcium administration. Pharmacotherapy 2011;31(10):298e-302e. DOI
  52. Vitekta [package insert]. Foster City, CA: Gilead Sciences, Inc.; 2014.
  53. Storan ER, O'Gorman SM, Murphy A, Laing M. Case Report of Calciphylaxis Secondary to Calcium and Vitamin D<sub>3</sub> Supplementation. J Cutan Med Surg. 2017;21(2):162-163. DOI
  54. Jenkins DJA, Spence JD, Giovannucci EL, et al. Supplemental vitamins and minerals for CVD prevention and treatment. J Am Coll Cardiol 2018;71(22):2570-84. PubMed
  55. Borkenhagen JF, Connor EL, Stafstrom CE. Neonatal hypocalcemic seizures due to excessive maternal calcium ingestion. Pediatr Neurol 2013;48(6):469-71. PubMed
  56. WHO recommendations on antenatal care for a positive pregnancy experience. Geneva: World Health Organization; 2016 (http://www.who.int/reproductivehealth/publications/maternal_perinatal_health/ anc-positive-pregnancy-experience/en/).
  57. Aune D, Navarro Rosenblatt DA, Chan DS, et al. Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies. Am J Clin Nutr. 2015;101(1):87-117. PubMed
  58. Lan T, Park Y, Colditz GA, et al. Adolescent dairy product and calcium intake in relation to later prostate cancer risk and mortality in the NIH-AARP Diet and Health Study. Cancer Causes Control. 2020;31(10):891-904. PubMed
  59. Zhang Y, Li Y, Liu J, et al. Association of Vitamin D or Calcium Supplementation with Cardiovascular Outcomes and Mortality: A Meta-Analysis with Trial Sequential Analysis. J Nutr Health Aging 2021;25(2):263-270. PubMed
  60. Myung SK, Kim HB, Lee YJ, Choi YJ, Oh SW. Calcium Supplements and Risk of Cardiovascular Disease: A Meta-Analysis of Clinical Trials. Nutrients 2021;13(2):368. PubMed
  61. Hetaimish B. Neonatal Calcinosis Cutis After Treatment of Hypocalcemia with Calcium Gluconate: A Report of 2 Cases. Am J Case Rep 2024;25:e943397. PubMed
  62. US Food and Drug Administration (FDA). Biktarvy Prescribing Information. October 2024. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/210251Orig1s020lbl.pdf. Accessed July 16, 2025.

See these in context on the Calcium monograph →

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

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team