Drug & supplement interaction

Iron + Alendronate Sodium, Cholecalciferol

Alendronate Sodium, Cholecalciferol brand name: Fosamax Plus D.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Iron has a moderate interaction with Alendronate Sodium, Cholecalciferol. Iron reduces the absorption of bisphosphonates.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Iron and Alendronate Sodium, Cholecalciferol

Here is the interaction we found between these two, with the evidence behind it.

Moderate

BISPHOSPHONATES

Why this applies to Alendronate Sodium, Cholecalciferol

Alendronate Sodium, Cholecalciferol falls under BISPHOSPHONATES — the group Iron interacts with.

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.
Severity Moderate Likelihood Probable Evidence D

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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version: alendronate (the bone-protecting part of Fosamax Plus D) is already hard for your body to absorb, even on a good day. When iron is in your stomach at the same time, the two can bind together and form a clump your gut can't take in. The worry isn't extra side effects, it's the opposite. You may end up absorbing less of your bone medicine, which means it may not protect your bones the way it should.

The good news is this is easy to manage. Fosamax is meant to be taken first thing in the morning with plain water, on an empty stomach, sitting upright. Just keep your iron well separated, at least two hours apart. If you're unsure how to space them, your pharmacist can help you map out a routine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Iron Also Interacts With Other Medications

Iron has 78 moderate, 1 minor known drug interactions in our database — the Alendronate Sodium, Cholecalciferol one above is one of them. If you take anything else, check it against the full list below.

Moderate 78 Minor 1 No known interaction 2,751 (incl. Alendronate Sodium, Cholecalciferol)
Taking anything else?

Check Another of Your Medications Against Iron

Covers the 2,830 medications we’ve checked against Iron. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Alendronate Sodium, Cholecalciferol

This page covers Iron only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Alendronate Sodium, Cholecalciferol page lists 25 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Calcium (moderate), Coffee (moderate), Coffee Charcoal (moderate) and Dolomite (moderate).

By severity: 1 major · 15 moderate · 9 minor.

From our pharmacist’s overview on the Alendronate Sodium, Cholecalciferol page

“Activated charcoal carries the only major rating against Fosamax Plus D (alendronate with cholecalciferol), and it deserves real respect from anyone taking this bone medicine. Charcoal soaks up drugs in the gut, so less alendronate ever reaches the skeleton it is supposed to strengthen.”

Reviewed by 2 · Jul 18, 2026

Open the Alendronate Sodium, Cholecalciferol interaction page

One more smart check

Taking Iron as Part of a Dietary Supplement Product? Check It for Interactions

We hold 16,325 real supplement products containing Iron, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Iron. Your product may carry other ingredients that interact with Alendronate Sodium, Cholecalciferol too, on top of Iron — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Iron and Alendronate Sodium, Cholecalciferol Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Iron
Top 1%

#14 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Alendronate Sodium, Cholecalciferol
Top half

#811 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Iron

What is Iron?

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

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.

Read the full Iron monograph & all interactions
Keep checking

Other Drugs & Iron

Browse every other medication we’ve checked against Iron — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
78Moderate
1Minor
2,750No known interaction
78 Moderate 1 Minor 2,750 No interaction
Moderate

78 interactions

Showing 60 of 78 moderate interactions — see all 78 on the Iron page.

Minor

1 interaction

No interaction 2,750 drugs checked — show the list

We also checked Iron against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,750 medications checked with no known interaction — see the full Iron list.

See the full Iron interactions page
See every supplement checked against Alendronate Sodium, Cholecalciferol, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

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

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

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

© 2021 Therapeutic Research Center, LLC

Keep exploring
Iron monograph › Uses, safety, and every drug interaction in one place Alendronate Sodium, Cholecalciferol supplement interactions › Every supplement checked against Alendronate Sodium, Cholecalciferol, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Iron and Alendronate Sodium, Cholecalciferol Together: Common Questions

Can you take Iron with Alendronate Sodium, Cholecalciferol?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Iron and Alendronate Sodium, Cholecalciferol interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Alendronate Sodium, Cholecalciferol and Iron?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.