Medication · bisphosphonate

Supplements and Alendronic acid.

Every documented pair, every citation. Below: 3 documented pairs grouped by mechanism.

Alendronic acid, sold under the brand names Fosamax, Fosavance, Binosto, is a bisphosphonate. Oral absorption is reduced by polyvalent cations including calcium, magnesium and iron.

Below are the 3 documented pairs we have explicitly assessed against Alendronic acid in the Distil database: 3 amber. The pairs cluster around 1 mechanism: Mineral chelation (absorption). Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.

Documented interactions

Mineral chelation (absorption)

Amber Calcium

Calcium binds to alendronic acid in the gut and almost completely blocks how much you absorb. Take alendronic acid first thing in the morning with plain water on an empty stomach, stay upright for 30 minutes, then wait at least two hours before any calcium-containing food, drink or supplement.

BNF: Alendronic acid

Amber Iron

Iron binds to alendronic acid in the gut and blocks absorption in the same way calcium does. Take alendronic acid first thing on an empty stomach with plain water, stay upright for 30 minutes, then wait at least two hours before any iron supplement.

BNF: Alendronic acid

Amber Magnesium Glycinate

Magnesium binds to alendronic acid in the gut and blocks absorption in the same way calcium does. Take alendronic acid first thing on an empty stomach with plain water, stay upright for 30 minutes, then wait at least two hours before any magnesium supplement.

BNF: Alendronic acid

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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Your supplements

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Your medications

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How we decide

How we grade severity, choose what's in scope, and what we exclude.

Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.

Read the full methodology

Something missing?

If a supplement or medication you take isn't in our autocomplete, tell us and we'll add it in the next quarterly update.

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Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a comprehensive personalised stack reasoned against this same database, the Distil report is the next step up.