Herb & supplement monograph

Iron Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Iron interacts with medications. The heart of this page is the interaction list — every drug Iron is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Iron is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Iron Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Iron drug interaction is moderate for most people, because iron can bind to many medicines in the gut and lower the amount the body absorbs. None of the listed interactions are rated major, but nearly all are moderate, and several are supported by human studies.

Interactions deserving the most attention

The best-documented concerns involve medicines where a drop in absorption can really matter. Human evidence shows iron can reduce absorption of levothyroxine, weakening thyroid control, and cut absorption of levodopa by around half, which could affect Parkinson's symptoms. Iron also lowers levels of HIV medicines such as dolutegravir, and can sharply reduce absorption of tetracycline and quinolone antibiotics, methyldopa (a blood pressure medicine), penicillamine, and bisphosphonates. In nearly all of these cases, the issue is timing rather than a dangerous reaction, and spacing doses apart is how it is typically managed.

What the rest of the list means

Although the list of interacting medicines is long, most share one simple mechanism: iron sticks to other drugs in the digestive tract so less gets absorbed. That does not make every combination harmful, and some predicted effects, such as with mycophenolate, have not shown meaningful changes in people.

Check your medications against Iron

Based on HelloPharmacist’s Iron interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Iron

80 medications have a known interaction with Iron, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Iron using our pharmacist-reviewed interaction data.

AI summaries are generated from our Iron interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Iron combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Iron affects

Every type of medication (drug category) Iron is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 13 drug categories Iron interacts with

Bictegravir/emtricitabine/tenofovir Alafenamide (biktarvy)BisphosphonatesDenosumab (prolia, Others)Dolutegravir (tivicay)Integrase InhibitorsLevodopaLevothyroxine (synthroid, Others)Methyldopa (aldomet)Mycophenolate Mofetil (cellcept)Penicillamine (cuprimine, Depen)Quinolone AntibioticsTetracycline AntibioticsChloramphenicol

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.

Likelihood Probable Evidence D

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.

Likelihood Probable Evidence D

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.

Likelihood Possible Evidence D

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%.

Likelihood Probable Evidence B

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.

Likelihood Possible Evidence D

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.

Likelihood Probable Evidence B

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.

Likelihood Probable Evidence B

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.

Likelihood Probable Evidence B

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.

Likelihood Unlikely Evidence D

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.

Likelihood Probable Evidence D

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.

Likelihood Probable Evidence D

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%.

Likelihood Probable Evidence D

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.

Likelihood Unlikely Evidence D

Monograph

Iron: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Iron is an essential mineral your body needs to make hemoglobin and carry oxygen in the blood. Supplements are mainly useful for treating or preventing iron deficiency and iron-deficiency anemia, ideally after a blood test confirms you are low. Because too much iron can be harmful, take it only when needed and under the guidance of a pharmacist or doctor.

Part used: Mineral (essential trace element)
Common forms: Tablets, capsules, liquid/drops, gummies, chewables, and intravenous (IV) preparations

People commonly use it for

Iron-deficiency anemia
Low iron stores during pregnancy
Fatigue from iron deficiency
Heavy menstrual blood loss
Restless legs syndrome (with low iron)

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally safe at recommended doses, but excess iron can be toxic and supplements should be used when there is a real need.

PregnancyLikely Safe

When used orally and appropriately. Iron is safe during pregnancy and breast-feeding in patients with adequate iron stores when used in doses below th...

Read the full pregnancy detail

BreastfeedingLikely Safe

When used orally and appropriately. Iron is safe during pregnancy and breast-feeding in patients with adequate iron stores when used in doses below th...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Iron is an essential mineral that your body needs to survive. It is a key part of hemoglobin, the protein in red blood cells that carries oxygen from your lungs to the rest of your body. Iron is also used to make myoglobin (a protein in muscle) and is needed for many other processes, including energy production.

You normally get iron from foods such as red meat, poultry, fish, beans, lentils, tofu, and iron-fortified cereals. When diet alone is not enough, or when blood loss or higher needs leave you short, iron supplements may be used to restore healthy levels.

Supplements come in several forms, such as ferrous sulfate, ferrous gluconate, and ferrous fumarate, as well as liquids, gummies, and IV products used in clinics for more serious deficiency.

How it works

Iron is a building block of hemoglobin and myoglobin, the proteins that carry and store oxygen. Without enough iron, your body cannot make enough healthy red blood cells, which leads to anemia and symptoms like fatigue and shortness of breath.

When you take an iron supplement, the iron is absorbed mostly in the small intestine and used by the bone marrow to make new red blood cells. Vitamin C can help your body absorb iron better, while certain foods and drinks (like tea, coffee, dairy, and high-calcium meals) can reduce absorption.

Your body has no easy way to get rid of extra iron, so it tightly controls how much it absorbs. This is why taking more iron than you need can lead to a harmful buildup over time.

Effectiveness

Does Iron work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 19 uses evaluated

3 Effective 4 Possibly effective 2 Leans ineffective 10 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Effective Anemia of chronic disease