Iron 18 mg Ingredients & Drug Interactions
by NOW
What is this page for?
First and foremost: checking Iron 18 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
Iron 18 mg is a dietary supplement by NOW with 1 active ingredient. Its ingredients are commonly taken for iron-deficiency anemia, low iron stores during pregnancy, fatigue from iron deficiency.Based on those ingredients, 80 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Iron. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against Iron 18 mg by NOW
Ask about any prescription or over-the-counter medication and we check it for interactions with Iron 18 mg by NOW — 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
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HelloPharmacist Scorecard of Iron 18 mg by NOW
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
NOW Iron 18 mg contains one active ingredient: iron (supplied as Ferrochel, a chelated form). The capsule also holds inactive ingredients — rice flour, hypromellose, stearic acid, and silicon dioxide — which are fillers and binders that make the capsule work.
Does it work?
Strong evidence
Iron is effective for iron deficiency anemia and anemia of chronic disease, which are the main reasons people take iron supplements. The data we hold also rates it possibly effective for heart failure, though that's a less common use.
Whether iron is right for you depends on whether you actually have low iron stores — talk with your pharmacist or doctor about getting tested first.
How safe is it?
Well-documented data
Iron is generally well tolerated when used at the right dose, but too much can be toxic, so use it only when there's a real need. The most common side effects are stomach upset — abdominal pain, constipation, diarrhea, nausea, and vomiting.
Serious side effects like ulcers are rare. In pregnancy, iron is often recommended and considered likely safe, but your prenatal care provider should guide the dose.
While breastfeeding, iron is generally considered acceptable at appropriate doses — check with your provider. The facts note debate in the research about whether high iron intake relates to heart disease risk, but most studies have found no link.
Meds to double-check
Moderate interaction found
Before taking this iron supplement, double-check if you use levodopa (Parkinson's disease), quinolone antibiotics (like ciprofloxacin), tetracycline antibiotics, levothyroxine (thyroid medication), bisphosphonates (bone medications), methyldopa (blood pressure medication), mycophenolate mofetil (immunosuppressant), or penicillamine. All are Moderate interactions.
Spacing doses 2–4 hours apart (depending on the drug) usually lowers the risk.
The bottom line
Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.
Iron 18 mg is a solid choice if you have iron deficiency anemia or anemia of chronic disease and your doctor or pharmacist has confirmed low iron. If you take levodopa, antibiotics, thyroid medication, bisphosphonates, blood pressure pills, or immunosuppressants, check them against the tool on this page first — spacing doses a few hours apart usually solves the problem.
Run any questions by your pharmacist before you start.
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 25, 2024.
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 Iron 18 mg, straight from the product label.
| Brand | NOW |
|---|---|
| Barcode (UPC) | 733739014436 |
| Net contents | 120 Veg Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Jul 25, 2024 |
| DSLD ID | 314399 |
| Product type | Mineral |
| Supplement form | Capsule |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Vegan, Vegetarian, Adult (18 - 50 Years), Kosher, Halal, Gluten Free |
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 Iron 18 mg by NOW, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| Iron | 18 mg | 100% |
| Ferrochel | 90 mg | -- |
Other ingredients: Rice Flour, Hypromellose, Stearic Acid, Silicon Dioxide
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.
Suggested/Recommended/Usage/Directions
Suggested Usage: Take 1 capsule daily with a meal.
Formula
Iron is an essential mineral that plays central roles in energy production, immune system function, and neurological health. Iron is an essential component of hemoglobin, a molecule that transports oxygen to the cells of the body, and myoglobin, which binds oxygen used in muscle tissues. NOW uses Ferrochel Iron Bisglycinate, which has clinically demonstrated superior absorption and is well tolerated because it is gentle and non-constipating.
Albion Minerals
Essential Mineral
Ferrochel Iron Bisglycinate
Triangle K (Kosher)
Crescent H (Halal)
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.
Precautions
Warning: Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6. Keep this product out of the reach of children. In case of accidental overdose, call a doctor or poison control center immediately.
Caution: For adults only. Keep out of reach of children.
Do not exceed recommended dosage unless directed by a physician.
Consult physician if pregnant/nursing, taking medication, or have a medical condition.
Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.
Formulation
Gentle & Non-Constipating
Non-GMO
Vegetarian/Vegan
Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients.
Natural color variation may occur in this product.
Made and quality tested in the USA with globally sourced ingredients.
FDA Statement of Identity
A Dietary Supplement
Seals/Symbols
Triangle K (Kosher)
GMP Quality Assured Crescent H (Halal)
General Statements
Minerals Family owned since 1968.
Brand IP Statement(s)
Ferrochel is a registered trademark of Albion Laboratories, Inc.
Storage
Store in a cool, dry place after opening.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
Iron 18 mg by NOW 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 Iron 18 mg by NOW
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Veg Capsule(s) Dosage formCapsule Servings per container120 Amounts shown are per serving.
Iron
Interacts with80 drugs
Iron is an essential mineral your body needs to make hemoglobin and carry oxygen in the blood. Supplements are mainly useful for treating or preventin...
Iron monograph & interactionsOther (inactive) ingredients: Rice Flour, Hypromellose, Stearic Acid, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.
Iron 18 mg by NOW Drug Interactions
HelloPharmacist Interaction Report
NOW Iron 18 mg can interact with several medication types, and most of these interactions are Moderate in severity.
The most serious concern is with levodopa (used for Parkinson's disease) — iron can reduce how much levodopa your body absorbs, potentially cutting levels by around half. You'll want to space them at least a couple of hours apart.
Read the full breakdown — every affected drug type, severity by severity
Iron also reduces absorption of quinolone antibiotics (like ciprofloxacin), tetracycline antibiotics, levothyroxine (thyroid medication), bisphosphonates (bone medications), methyldopa (blood pressure medication), mycophenolate mofetil (an immunosuppressant), and penicillamine (used for Wilson's disease and rheumatoid arthritis). All of these are Moderate interactions.
The general rule: separate iron from these drugs by at least 2 hours, though tetracyclines need extra space — take iron at least 2 hours before or 4 hours after. Altogether, these interactions span 79 individual medications.
Since iron works by binding to these drugs in your stomach and blocking their absorption, timing is your main defense. Use the medication checker on this page with your exact prescriptions to see if any apply to you.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against Iron 18 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 Iron 18 mg interact with 80 drugs. Click any drug to see the details.
1 of the 1 ingredient in Iron 18 mg interact with drugs. Each result below shows which ingredient is responsible. Iron
AlendronateBinosto, Fosamax
How Alendronate interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBisphosphonates Moderate
Interaction Summary
Iron reduces the absorption of bisphosphonates.
Read the full Ferrochel + Alendronate interactionAlendronate Sodium
How Alendronate Sodium interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBisphosphonates Moderate
Interaction Summary
Iron reduces the absorption of bisphosphonates.
Read the full Ferrochel + Alendronate Sodium interactionAlendronate Sodium, CholecalciferolFosamax Plus D
How Alendronate Sodium, Cholecalciferol interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBisphosphonates Moderate
Interaction Summary
Iron reduces the absorption of bisphosphonates.
Read the full Ferrochel + Alendronate Sodium, Cholecalciferol interactionAmphotericin, TetracyclineMysteclin-F
How Amphotericin, Tetracycline interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Amphotericin, Tetracycline interactionBenserazide, LevodopaMadopar, Prolopa
How Benserazide, Levodopa interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelLevodopa Moderate
Interaction Summary
Iron might decrease levodopa levels by reducing its absorption.
Read the full Ferrochel + Benserazide, Levodopa interactionBictegravir, Emtricitabine, Tenofovir AlafenamideBiktarvy
How Bictegravir, Emtricitabine, Tenofovir Alafenamide interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Bictegravir, Emtricitabine, Tenofovir Alafenamide interactionBismuth Subsalicylate, Metronidazole, TetracyclineHelidac
How Bismuth Subsalicylate, Metronidazole, Tetracycline interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Bismuth Subsalicylate, Metronidazole, Tetracycline interactionCarbidopa, LevodopaDhivy, Rytary, Sinemet, Sinemet CR
How Carbidopa, Levodopa interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelLevodopa Moderate
Interaction Summary
Iron might decrease levodopa levels by reducing its absorption.
Read the full Ferrochel + Carbidopa, Levodopa interactionCarbidopa, Levodopa, EntacaponeStalevo
How Carbidopa, Levodopa, Entacapone interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelLevodopa Moderate
Interaction Summary
Iron might decrease levodopa levels by reducing its absorption.
Read the full Ferrochel + Carbidopa, Levodopa, Entacapone interactionChlorothiazide, MethyldopaAldochlor, Aldoclor 150, Aldoclor 250
How Chlorothiazide, Methyldopa interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelMethyldopa (aldomet) Moderate
Interaction Summary
Iron might decrease methyldopa levels by reducing its absorption.
Read the full Ferrochel + Chlorothiazide, Methyldopa interactionChlortetracyclineAureomycin
How Chlortetracycline interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Chlortetracycline interactionCinoxacinCinobac
How Cinoxacin interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelQuinolone Antibiotics Moderate
Interaction Summary
Iron might decrease levels of quinolone antibiotics by reducing their absorption.
Read the full Ferrochel + Cinoxacin interactionCiprofloxacinCiloxan, Cipro, Cipro IV, Cipro XR, Ciprobay, Otiprio
How Ciprofloxacin interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelQuinolone Antibiotics Moderate
Interaction Summary
Iron might decrease levels of quinolone antibiotics by reducing their absorption.
Read the full Ferrochel + Ciprofloxacin interactionClinafloxacinClinafloxacin
How Clinafloxacin interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelQuinolone Antibiotics Moderate
Interaction Summary
Iron might decrease levels of quinolone antibiotics by reducing their absorption.
Read the full Ferrochel + Clinafloxacin interactionCobicistat, Elvitegravir, Emtricitabine, Tenofovir Alafenamide FumarateGenvoya
How Cobicistat, Elvitegravir, Emtricitabine, Tenofovir Alafenamide Fumarate interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Cobicistat, Elvitegravir, Emtricitabine, Tenofovir Alafenamide Fumarate interactionDarunavir, Cobicistat, Emtricitabine, Tenofovir AlafenamideSymtuza
How Darunavir, Cobicistat, Emtricitabine, Tenofovir Alafenamide interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Darunavir, Cobicistat, Emtricitabine, Tenofovir Alafenamide interactionDemeclocyclineDeclomycin
How Demeclocycline interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Demeclocycline interactionDenosumabProlia, XGEVA
How Denosumab interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelDenosumab (prolia, Others) Moderate
Interaction Summary
Administration of intravenous iron within one month of denosumab administration might increase the risk of severe hypophosphatemia and hypocalcemia.
Read the full Ferrochel + Denosumab interactionDolutegravirTivicay
How Dolutegravir interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelDolutegravir (tivicay) Moderate
Interaction Summary
Iron might decrease dolutegravir levels by reducing its absorption.
Read the full Ferrochel + Dolutegravir interactionDolutegravir, Emtricitabine, Tenofovir AlafenamideDolutegravir, Emtricitabine, Tenofovir Alafenamide
How Dolutegravir, Emtricitabine, Tenofovir Alafenamide interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelDolutegravir (tivicay), Bictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease dolutegravir levels by reducing its absorption.
Read the full Ferrochel + Dolutegravir, Emtricitabine, Tenofovir Alafenamide interactionDolutegravir, RilpivirineJuluca
How Dolutegravir, Rilpivirine interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelDolutegravir (tivicay) Moderate
Interaction Summary
Iron might decrease dolutegravir levels by reducing its absorption.
Read the full Ferrochel + Dolutegravir, Rilpivirine interactionDoripenemDoribax
How Doripenem interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelQuinolone Antibiotics, Tetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of quinolone antibiotics by reducing their absorption.
Read the full Ferrochel + Doripenem interactionDoxycyclineDoryx, Doxy, Doxy-D, Doxycin, Doxycycline Injection, Doxylin +6 more
How Doxycycline interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Doxycycline interactionDoxycycline HyclateActiclate, Acticlate Cap, Lymepak
How Doxycycline Hyclate interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Doxycycline Hyclate interactionDoxycycline MonohydrateErfacea
How Doxycycline Monohydrate interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Doxycycline Monohydrate interactionDoxycylineDoxychel
How Doxycyline interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelTetracycline Antibiotics Moderate
Interaction Summary
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Read the full Ferrochel + Doxycyline interactionElvitegravir, Cobicistat, Emtricitabine, Tenofovir Disoproxil FumarateStribild
How Elvitegravir, Cobicistat, Emtricitabine, Tenofovir Disoproxil Fumarate interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Elvitegravir, Cobicistat, Emtricitabine, Tenofovir Disoproxil Fumarate interactionEmtricitabineEmtriva
How Emtricitabine interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Emtricitabine interactionEmtricitabine, Rilpivirine, TenofovirComplera
How Emtricitabine, Rilpivirine, Tenofovir interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Emtricitabine, Rilpivirine, Tenofovir interactionEmtricitabine, Rilpivirine, Tenofovir AlafenamideOdefsey
How Emtricitabine, Rilpivirine, Tenofovir Alafenamide interacts with Iron 18 mg — through 1 ingredient. Tap an ingredient for the detail:
FerrochelBictegravir/emtricitabine/tenofovir Alafenamide (biktarvy) Moderate
Interaction Summary
Iron might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Read the full Ferrochel + Emtricitabine, Rilpivirine, Tenofovir Alafenamide interactionEach ingredient & the kinds of drugs it affects
For each ingredient in Iron 18 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.
Iron
Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy)
Iron 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 iron 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, iron containing products.
Bisphosphonates
Iron reduces the absorption of bisphosphonates.
Advise patients that doses of bisphosphonates should be separated by at least two hours from doses of all other medications, including supplements such as iron. Divalent cations, including iron, can decrease absorption of bisphosphonates by forming insoluble complexes in the gastrointestinal tract.
Denosumab (Prolia, Others)
Administration of intravenous iron within one month of denosumab administration might increase the risk of severe hypophosphatemia and hypocalcemia.
A case of severe hypocalcemia (albumin corrected calcium 6.88 mg/dL, ionized calcium 3.68 mg/dL) and hypophosphatemia (<0.5 mg/dL) with respiratory acidosis, QT interval prolongation, and nonsustained ventricular tachycardia was reported in a 76-year-old male who had received an iron polymaltose infusion within 2 weeks of a subcutaneous injection of denosumab. Serum parathyroid hormone was also elevated (348 pg/mL). Subsequent iron infusions with iron polymaltose and ferric carboxymaltose were followed by transient hypophosphatemia, but without hypocalcemia. Additionally, a literature review describes 6 additional cases of hypophosphatemia and hypocalcemia in patients 52-92 years of age who had been administered intravenous iron as either ferric carboxymaltose or iron polymaltose and subcutaneous denosumab within 1-4 weeks of each other.
Dolutegravir (Tivicay)
Iron might decrease dolutegravir levels by reducing its absorption.
Advise patients to take dolutegravir at least 2 hours before or 6 hours after taking iron. Pharmacokinetic research shows that iron can decrease the absorption of dolutegravir from the gastrointestinal tract through chelation. When taken under fasting conditions, a single dose of ferrous fumarate 324 mg orally along with dolutegravir 50 mg reduces overall exposure to dolutegravir by 54%.
Integrase Inhibitors
Theoretically, taking iron along with integrase inhibitors might decrease the levels and clinical effects of these drugs.
Iron is a divalent cation. There is concern that iron may decrease the absorption of integrase inhibitors from the gastrointestinal tract through chelation. One pharmacokinetic study shows that iron can decrease blood levels of the specific integrase inhibitor dolutegravir through chelation. Also, other pharmacokinetic research shows that other divalent cations such as calcium can decrease the absorption and levels of some integrase inhibitors through chelation.
Levodopa
Iron might decrease levodopa levels by reducing its absorption.
Advise patients to separate doses of levodopa and iron as much as possible. There is some evidence in healthy people that iron forms chelates with levodopa, reducing the amount of levodopa absorbed by around 50%. The clinical significance of this hasn't been determined.
Levothyroxine (Synthroid, Others)
Iron might decrease levothyroxine levels by reducing its absorption.
Advise patients to separate levothyroxine and iron doses by at least 2 hours. Iron can decrease the absorption and efficacy of levothyroxine by forming insoluble complexes in the gastrointestinal tract.
Methyldopa (Aldomet)
Iron might decrease methyldopa levels by reducing its absorption.
Advise patients to separate methyldopa and iron doses by at least 2 hours. Iron can decrease the absorption of methyldopa from the gastrointestinal tract through chelation, resulting in increases in blood pressure.
Mycophenolate Mofetil (Cellcept)
Theoretically, iron might decrease mycophenolate mofetil levels by reducing its absorption.
Advise patients to take iron 4-6 hours before, or 2 hours after, mycophenolate mofetil. It has been suggested that a decrease of absorption is possible, probably by forming nonabsorbable chelates. However, mycophenolate pharmacokinetics are not affected by iron supplementation in available clinical research.
Penicillamine (Cuprimine, Depen)
Iron might decrease penicillamine levels by reducing its absorption.
Advise patients to separate penicillamine and iron doses by at least 2 hours. Oral iron supplements can reduce absorption of penicillamine by 30% to 70%, probably due to chelate formation. In people with Wilson's disease, this interaction has led to reduced efficacy of penicillamine.
Quinolone Antibiotics
Iron might decrease levels of quinolone antibiotics by reducing their absorption.
Advise patients to separate quinolone antibiotics and iron doses by at least 2 hours. Iron decreases the absorption of quinolones due to formation of insoluble complexes in the gastrointestinal tract.
Tetracycline Antibiotics
Iron might decrease levels of tetracycline antibiotics by reducing their absorption.
Advise patients to take iron at least 2 hours before or 4 hours after tetracycline antibiotics. Concomitant use can decrease absorption of tetracycline antibiotics from the gastrointestinal tract by 50% to 90%.
Chloramphenicol
Theoretically, taking chloramphenicol with iron might reduce the response to iron therapy in iron deficiency anemia.
Chloramphenicol interferes with erythrocyte maturation. However, since chloramphenicol isn't usually taken for prolonged periods, this isn't likely to be clinically significant.
Brand information
Manufacturer and brand details for Iron 18 mg, from the product label.
NOW
See all NOW products- Name
- NOW Foods
- Street Address
- 395 S. Glen Ellyn Rd.
- City
- Bloomingdale
- State
- IL
- ZipCode
- 60108
- Web Address
- nowfoods.com
Iron 18 mg by NOW: Common Questions
Does Iron 18 mg by NOW interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Will iron supplements actually help my anemia?
What side effects might I notice?
Is iron safe during pregnancy and breastfeeding?
Can I take iron with my thyroid medication?
How do I avoid iron blocking my other medications?
Is there iron in this supplement, or just the brand name Ferrochel?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if Iron 18 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 Iron 18 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
Iron 18 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 72 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.
Iron 72 references
- McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
- Bruner AB, Joffe A, Duggan AK, et al. Randomized study of cognitive effects of iron supplementation in non- anaemic iron-deficient adolescent girls. Lancet 1996;348:992-6.
- Ullen H, Augustsson K, Gustavsson C, Steineck G. Supplementary iron intake and risk of cancer: reversed causality? Cancer Lett 1997;114:215-6.
- Reunanen A, Takkunen H, Knekt P, et al. Body iron stores, dietary iron intake and coronary heart disease mortality. J Intern Med 1995;238:223-30. PubMed
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