Can I take 0.35mg and Calcium together?
Drug interaction guide
Originally published 12 May 2026
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Calcium supplements can significantly reduce the amount of levothyroxine your body absorbs. This can make your thyroid medication less effective, potentially leading to symptoms of an underactive thyroid, such as tiredness, weight gain, and feeling cold.
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Why this happens
Calcium carbonate or other calcium salts bind to the levothyroxine in your stomach or intestines. This creates a complex that is too large for your body to absorb into the bloodstream, meaning the medicine passes through your system without working.
What you should do
Back to contentsYou should separate the time you take these two by at least 4 hours. It is usually best to take your levothyroxine on an empty stomach first thing in the morning, and wait until lunch or dinner time to take your calcium 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.
12 May 2026 | Originally published
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