Can I take A1 cal d and Alendronic acid together?
Drug interaction guide
Originally published 14 Mar 2026
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Taking these two medicines at the same time can stop the alendronic acid from working properly. The calcium in the A1 Cal D binds to the alendronic acid in your stomach, preventing your body from absorbing it into your bloodstream.
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Why this happens
Calcium carbonate (in A1 Cal D) forms insoluble complexes with alendronic acid in the gastrointestinal tract. This significantly reduces the bioavailability (absorption) of the alendronic acid, making it less effective at strengthening your bones.
What you should do
Back to contentsYou must separate these medicines. Take your alendronic acid first thing in the morning on an empty stomach with a full glass of plain water. Wait at least 30 minutes (ideally 60 minutes) before eating, drinking anything else, or taking any other medicines, including your A1 Cal D supplement.
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Using other medicines
Back to contentsTaking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
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Article history
The information on this page is written and peer reviewed by qualified clinicians.
14 Mar 2026 | Originally published

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