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Can I take Levothyroxine 25 and Vitamin d3 together?

Drug interaction guide

There is no direct harmful interaction between levothyroxine and vitamin D3. In fact, many people take them together because vitamin D deficiency is common in people with thyroid conditions. However, the timing of when you take them is important to ensure your thyroid medication works properly.

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Why this happens

While vitamin D itself doesn't interfere with levothyroxine, many vitamin D supplements also contain calcium. Calcium is known to bind to levothyroxine in the stomach, which prevents the thyroid medicine from being absorbed into your bloodstream. Even if your supplement only contains vitamin D, taking it at the same time as your thyroid pill can sometimes interfere with the very specific conditions needed for levothyroxine to be absorbed.

What you should do

You should take your levothyroxine on an empty stomach, at least 30 to 60 minutes before breakfast. To be safe, wait at least 4 hours after taking your levothyroxine before taking your vitamin D3 supplement. This ensures your body gets the full dose of your thyroid medication.

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Using other medicines

Taking 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.

  • 25 Jan 2026 | Originally published
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