B-1 100 mg Ingredients & Drug Interactions
by Source Naturals
What is this page for?
First and foremost: checking B-1 100 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
B-1 100 mg is a dietary supplement by Source Naturals 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, 171 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Calcium, Thiamine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against B-1 100 mg by Source Naturals
Ask about any prescription or over-the-counter medication and we check it for interactions with B-1 100 mg by Source Naturals — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
Ask the Pharmacist
A licensed pharmacist will answer your question by email — free, usually within 24 hours.
Got it — thank you!
A licensed pharmacist will answer within 24 hours. Keep an eye on your email (worth checking spam, just in case).
HelloPharmacist Scorecard of B-1 100 mg by Source Naturals
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.
What’s inside
Full disclosure
This product contains 2 active ingredients: calcium and thiamine (vitamin B1). Calcium is an essential mineral needed to build and maintain bone, support muscle and nerve function, and manage blood pressure and heart rhythm.
Thiamine is a B vitamin your body uses to convert food into energy and to keep your nervous system and muscles working properly. Both are micronutrients your body cannot make on its own, so they must come from food or supplements.
Does it work?
Strong evidence
Calcium is established as effective for preventing kidney failure, treating dyspepsia (indigestion), correcting low blood calcium (hypocalcemia), managing high blood potassium (hyperkalemia), and is likely effective for osteoporosis. Thiamine is effective for thiamine deficiency and Wernicke-Korsakoff syndrome (a serious brain condition from severe thiamine lack).
It is possibly effective for menstrual cramps (dysmenorrhea); evidence for mosquito repellent and heart failure is insufficient.
How safe is it?
Well-documented data
Calcium is generally well tolerated when taken at recommended doses. The most common side effects are belching, constipation, diarrhea, bloating, and stomach upset.
High doses raise concerns about rare problems like kidney stones. There is some epidemiological concern that very high intakes (over 1500–2000 mg daily) might increase prostate cancer risk and possibly cardiovascular disease risk, though research on these points remains debated.
Thiamine taken by mouth is very safe in normal amounts; allergic reactions are extremely rare. High-dose intravenous thiamine can rarely trigger severe allergic reactions, but oral forms do not carry this risk.
Meds to double-check
Major interaction found
If you take dolutegravir or elvitegravir (HIV integrase inhibitors), do not take this product at the same time — separate them by hours as noted above. The same timing matters for ceftriaxone (an injectable antibiotic), levothyroxine (thyroid hormone), sotalol (heart medication), raltegravir (HIV drug), or diltiazem (blood pressure medication).
If you use calcipotriene skin cream, mention the calcium supplement to your doctor. Trimethoprim (an antibiotic) is the only other medication with documented interaction data for this product — it's minor.
The bottom line
Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Major medication interactions have been identified, and safety information is well characterized.
This calcium and thiamine combination is useful if you need to correct a deficiency or support bone health. However, if you take HIV medications (dolutegravir, elvitegravir, raltegravir), thyroid hormone, heart medications, or the antibiotic ceftriaxone, you'll need to time doses carefully — sometimes hours apart.
Talk to your pharmacist about your exact medications before you start.
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 Jan 25, 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
General information
Key facts about B-1 100 mg, straight from the product label.
| Brand | Source Naturals |
|---|---|
| Barcode (UPC) | 021078004080 |
| Net contents | 250 Tablet(s) |
| Market status | On market |
| Date entered into DSLD | Jan 25, 2020 |
| DSLD ID | 211767 |
| Product type | Single Vitamin And Mineral |
| Supplement form | Tablet Or Pill |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years) |
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 B-1 100 mg by Source Naturals, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| Calcium | 35 mg | 4% |
| Thiamine | 100 mg | 6667% |
Other ingredients: Dibasic Calcium Phosphate, Stearic Acid, modified Cellulose Gum, Silica
Tap any ingredient to jump to its full detail below.
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.
FDA Statement of Identity
Dietary Supplement
Formula
Thiamin
Vitamin B-1 (thiamin) is essential for the metabolism of carbohydrates, some amino acids and alcohol. It is also necessary for the production of the neurotransmitter acetylcholine, and for the detoxification of both alcohol and lactic acid (a by-product of strenuous exercise). Thiamin has important roles in the production of energy and ATP derived from reactions in the Krebs cycle. A high carbohydrate diet, strenuous physical exercise, or chronic alcohol consumption may increase the physiological need for vitamin B-1.
Formulation
Supports energy production
Suggested/Recommended/Usage/Directions
Suggested Use: 1 tablet daily.
Precautions
Note: If you are pregnant, may become pregnant, or breastfeeding, consult your health care professional before using this product.
Do not use if either tamper-evident seal is broken or missing.
Keep out of the reach of children.
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.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
B-1 100 mg by Source Naturals label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
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)The Ingredients in B-1 100 mg by Source Naturals
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 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 with168 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 f...
Calcium monograph & interactionsThiamine
Interacts with3 drugs
Thiamine (vitamin B1) is an essential nutrient your body needs to turn food into energy and to keep your nerves and heart healthy. Most people get eno...
Thiamine monograph & interactionsOther (inactive) ingredients: Dibasic Calcium Phosphate, Stearic Acid, Modified Cellulose Gum, Silica. These complete the product’s ingredient list but are not active constituents.
B-1 100 mg by Source Naturals Drug Interactions
HelloPharmacist Interaction Report
Source Naturals B-1 100 mg contains calcium, which interacts with a number of medications — most seriously with HIV integrase inhibitors and an antibiotic.
The biggest concern is dolutegravir (Tivicay), an HIV medication: calcium can cut dolutegravir levels by nearly 40%, which may reduce its effectiveness. You'll need to take dolutegravir either 2 hours before or 6 hours after your calcium dose.
The same applies to elvitegravir (Vitekta), another HIV integrase inhibitor, though you'd separate those by 2 hours before or after calcium instead.
Read the full breakdown — every affected drug type, severity by severity
Calcium also carries a serious risk with ceftriaxone (Rocephin), an injectable antibiotic — they can form a dangerous salt together in your lungs and kidneys. If you take ceftriaxone by vein, do not get intravenous calcium (including in nutritional fluids) within 48 hours.
Additionally, calcium reduces absorption of the thyroid hormone levothyroxine (Synthroid) and the heart medication sotalol (Betapace); separate each by at least 4 hours. Calcium may modestly lower raltegravir (Isentress), another HIV drug, though usually without needing a dose change.
It may also reduce diltiazem (Cardizem), a blood pressure and heart medication. Finally, if you use calcipotriene (Dovonex) cream for psoriasis, adding calcium raises the theoretical risk of dangerously high blood calcium levels.
Thiamine, the other ingredient, does not interact with most medications. Altogether, these interactions span 170 individual medications.
Check your exact prescriptions with the tool below before you start.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against B-1 100 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 checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in B-1 100 mg interact with 171 drugs. Click any drug to see the details.
2 of the 2 ingredients in B-1 100 mg interact with drugs. Each result below shows which ingredient is responsible. Calcium Thiamine
Bendroflumethiazide, PotassiumCentyl K, Neo-NaClex-K
How Bendroflumethiazide, Potassium interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Bendroflumethiazide, Potassium interactionBendroflumethiazide, Rauwolfia SerpentinaRauzide
How Bendroflumethiazide, Rauwolfia Serpentina interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Bendroflumethiazide, Rauwolfia Serpentina interactionBenzthiazideExna
How Benzthiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Benzthiazide interactionBetamethasone Dipropionate, CalcipotrieneEnstilar, Wynzora
How Betamethasone Dipropionate, Calcipotriene interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumCalcipotriene (dovonex) Moderate
Interaction Summary
Taking calcipotriene with calcium might increase the risk for hypercalcemia.
Read the full Calcium + Betamethasone Dipropionate, Calcipotriene interactionBictegravir, Emtricitabine, Tenofovir AlafenamideBiktarvy
How Bictegravir, Emtricitabine, Tenofovir Alafenamide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Calcium might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Calcium + Bictegravir, Emtricitabine, Tenofovir Alafenamide interactionBismuth Subsalicylate, Metronidazole, TetracyclineHelidac
How Bismuth Subsalicylate, Metronidazole, Tetracycline interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumTetracycline Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of tetracycline antibiotics.
Read the full Calcium + Bismuth Subsalicylate, Metronidazole, Tetracycline interactionBisoprolol, HydrochlorothiazideZiac
How Bisoprolol, Hydrochlorothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Bisoprolol, Hydrochlorothiazide interactionCalcipotrieneDovonex
How Calcipotriene interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumCalcipotriene (dovonex) Moderate
Interaction Summary
Taking calcipotriene with calcium might increase the risk for hypercalcemia.
Read the full Calcium + Calcipotriene interactionCandesartan Cilexetil, HydrochlorothiazideAtacand HCT
How Candesartan Cilexetil, Hydrochlorothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Candesartan Cilexetil, Hydrochlorothiazide interactionCaptopril, HydrochlorothiazideAcezide, Capozide
How Captopril, Hydrochlorothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Captopril, Hydrochlorothiazide interactionChlorothiazideDiuril
How Chlorothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Chlorothiazide interactionChlorothiazide, MethyldopaAldochlor, Aldoclor 150, Aldoclor 250
How Chlorothiazide, Methyldopa interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Chlorothiazide, Methyldopa interactionChlorothiazide, ReserpineDiupres
How Chlorothiazide, Reserpine interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Chlorothiazide, Reserpine interactionChlortetracyclineAureomycin
How Chlortetracycline interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumTetracycline Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of tetracycline antibiotics.
Read the full Calcium + Chlortetracycline interactionChlorthalidoneHygroton, Thalitone
How Chlorthalidone interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Chlorthalidone interactionChlorthalidone, ClonidineClorpres, Combipres
How Chlorthalidone, Clonidine interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Chlorthalidone, Clonidine interactionCinoxacinCinobac
How Cinoxacin interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumQuinolone Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of quinolone antibiotics.
Read the full Calcium + Cinoxacin interactionCiprofloxacinCiloxan, Cipro, Cipro IV, Cipro XR, Ciprobay, Otiprio
How Ciprofloxacin interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumQuinolone Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of quinolone antibiotics.
Read the full Calcium + Ciprofloxacin interactionClinafloxacinClinafloxacin
How Clinafloxacin interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumQuinolone Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of quinolone antibiotics.
Read the full Calcium + Clinafloxacin interactionCryptenamine, MethyclothiazideDiutensen
How Cryptenamine, Methyclothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Cryptenamine, Methyclothiazide interactionCyclothiazideAnhydron, Fluidil
How Cyclothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Cyclothiazide interactionDarunavir, Cobicistat, Emtricitabine, Tenofovir AlafenamideSymtuza
How Darunavir, Cobicistat, Emtricitabine, Tenofovir Alafenamide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Calcium might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Calcium + Darunavir, Cobicistat, Emtricitabine, Tenofovir Alafenamide interactionDemeclocyclineDeclomycin
How Demeclocycline interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumTetracycline Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of tetracycline antibiotics.
Read the full Calcium + Demeclocycline interactionDeserpidine, HydrochlorothiazideOreticyl, Oreticyl Forte
How Deserpidine, Hydrochlorothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Deserpidine, Hydrochlorothiazide interactionDeserpidine, MethyclothiazideEnduronyl, Enduronyl Forte
How Deserpidine, Methyclothiazide interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumThiazide Diuretics Moderate
Interaction Summary
Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Read the full Calcium + Deserpidine, Methyclothiazide interactionDigoxinDigitek, Lanoxicaps, Lanoxin
How Digoxin interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumDigoxin (lanoxin) Moderate
Interaction Summary
Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.
Read the full Calcium + Digoxin interactionDihydroxyaluminum Sodium CarbonateRolaids
How Dihydroxyaluminum Sodium Carbonate interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumAluminum Moderate
Interaction Summary
Calcium citrate might increase aluminum absorption and toxicity.
Read the full Calcium + Dihydroxyaluminum Sodium Carbonate interactionDiltiazemAdizem-SR, Adizem-XL, Angitil SR, Angitil XL, Calcicard CR, Cardizem +23 more
How Diltiazem interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumCalcium Channel Blockers, Diltiazem (cardizem, Others) Moderate
Interaction Summary
Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Read the full Calcium + Diltiazem interactionDiltiazem, EnalaprilTeczem
How Diltiazem, Enalapril interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumCalcium Channel Blockers, Diltiazem (cardizem, Others) Moderate
Interaction Summary
Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Read the full Calcium + Diltiazem, Enalapril interactionDoripenemDoribax
How Doripenem interacts with B-1 100 mg — through 1 ingredient. Tap an ingredient for the detail:
CalciumQuinolone Antibiotics, Tetracycline Antibiotics Moderate
Interaction Summary
Calcium seems to reduce the absorption of quinolone antibiotics.
Read the full Calcium + Doripenem interactionEach ingredient & the kinds of drugs it affects
For each ingredient in B-1 100 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.
Calcium
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Thiamine
Trimethoprim (Proloprim)
Trimethoprim might increase blood levels of thiamine.
In vitro, animal, and clinical research suggest that trimethoprim inhibits intestinal thiamine transporter ThTR-2, hepatic transporter OCT1, and renal transporters OCT2, MATE1, and MATE2, resulting in paradoxically increased thiamine plasma concentrations.
Brand information
Manufacturer and brand details for B-1 100 mg, from the product label.
Source Naturals
- Name
- Source Naturals, Inc.
- Street Address
- P. O. Box 2118
- City
- Santa Cruz
- State
- CA
- ZipCode
- 95062
- Web Address
- www.sourcenaturals.com
B-1 100 mg by Source Naturals: Common Questions
Does B-1 100 mg by Source Naturals interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
What is this product actually for?
Can I take this if I'm pregnant or breastfeeding?
What side effects might I get?
Why do I have to space this apart from my other medications?
Is this safe to take every day?
Does it matter what brand I pick?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if B-1 100 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
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.
The Full Monographs Behind B-1 100 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Calcium
Interacts with 168 drugsCalcium 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 monographThiamine
Interacts with 3 drugsThiamine (vitamin B1) is an essential nutrient your body needs to turn food into energy and to keep your nerves and heart healthy. Most people get enough from food, but supplements are clear...
Read the full Thiamine monograph →Sources & How We Checked
B-1 100 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.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
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 69 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
- Shils M, Olson A, Shike M. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, PA: Lea and Febiger, 1994.
- 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
- 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
- Maton PN, Burton ME. Antacids revisited: a review of their clinical pharmacology and recommended therapeutic use. Drugs 1999;57:855-70.
- Clemens JD, Feinstein AR. Calcium carbonate and constipation: a historical review of medical mythopoeia. Gastroenterology 1977;72:957-61. DOI
- 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
- Friedman PA, Bushinsky DA. Diuretic effects on calcium metabolism. Semin Nephrol 1999;19:551-6.
- Koo WK, Walters JC, Esterlitz J, et al. Maternal calcium supplementation and fetal bone mineralization. Obstet Gynecol 1999;94:577-82. DOI
- 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
- Murry JJ, Healy MD. Drug-mineral interactions: a new responsibility for the hospital dietician. J Am Diet Assoc 1991;91:66-73.
- 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.
- Butner LE, Fulco PP, Feldman G, et al. Calcium carbonate-induced hypothyroidism. Ann Intern Med 2000:132:595. PubMed
- Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. JAMA 1998;279:750. PubMed
- 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
- Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA 2000;283:2822-5. PubMed
- 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
- 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
- Bar-Or D, Yoel G. Calcium and calciferol antagonize effect of verapamil in atrial fibrillation. Br Med J 1981;282:1585-6.
- 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
- Simoneau G. Absence of rebound effect with calcium carbonate. Eur J Drug Metab Pharmacokinet 1996;21:351-7. PubMed
- 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
- 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.
- Gueguen L, Pointillart A. The bioavailability of dietary calcium. J Am Coll Nutr 2000;19:119s-136s. PubMed
- Vella A, Gerber TC, Hayes DL, Reeder GS. Digoxin, hypercalcaemia, and cardiac conduction. Postgrad Med J 1999;75:554-6. PubMed
- 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
- 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
- Weingarten MA, Zalmanovici A, Yaphe J. Dietary calcium supplementation for preventing colorectal cancer and adenomatous polyps. Cochrane Database Syst Rev 2004;(1):CD003548. PubMed
- 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
- 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
- Rocephin (ceftriaxone) and calcium interaction. Pharmacist's Letter / Prescriber's Letter 2007;23(10):231005.
- 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.
- 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
- Calcium supplementation and vascular events. Pharmacist's Letter / Prescriber's Letter 2008;24(3):240306.
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- Grove ML, Cook D. Calcium and heart attacks. Doesn't apply to most calcium prescriptions. BMJ. 2010;341:c5003. PubMed
- Insentress [package insert]. Whitehouse Station, NJ: Merck Sharp & Dohme Corp.; 2014.
- 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
- Vitekta [package insert]. Foster City, CA: Gilead Sciences, Inc.; 2014.
- 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
- 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
- Borkenhagen JF, Connor EL, Stafstrom CE. Neonatal hypocalcemic seizures due to excessive maternal calcium ingestion. Pediatr Neurol 2013;48(6):469-71. PubMed
- 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/).
- 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
- 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
- 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
- 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
- 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
- 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.
Thiamine 7 references
- McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
- Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
- 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
- Rogovik, A. L., Vohra, S., and Goldman, R. D. Safety considerations and potential interactions of vitamins: should vitamins be considered drugs? Ann.Pharmacother. 2010;44(2):311-324. PubMed
- Arruti N, Bernedo N, Audicana MT, Villarreal O, Uriel O, Muñoz D. Systemic allergic dermatitis caused by thiamine after iontophoresis. Contact Dermatitis. 2013 Dec;69(6):375-6. PubMed
- Thiamine hydrochloride injection package insert. Lake Zurich, IL: Fresenius Kabi, LLC; September 2019.
- Vora B, Wen A, Yee SW, et al. The Effect of Trimethoprim on Thiamine Absorption: A Transporter-Mediated Drug-Nutrient Interaction. Clin Pharmacol Ther 2023;114(2):381-392.
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