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Can I take 12.5mg and Fibre supplements together?

Drug interaction guide

Taking fibre supplements at the same time as levothyroxine can stop your body from absorbing the medicine properly. This means you might not get the full dose of thyroid hormone you need, which could lead to symptoms of an underactive thyroid, such as feeling tired, cold, or gaining weight.

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Why this happens

Fibre acts like a sponge in your stomach and intestines. It can bind to the levothyroxine molecules, trapping them and carrying them out of your body before they have a chance to enter your bloodstream.

What you should do

You do not need to stop taking fibre, but you must space them out. Take your levothyroxine on an empty stomach, at least 30 to 60 minutes before breakfast. Wait at least 4 hours after taking your levothyroxine before taking a fibre supplement (like psyllium husk, Fybogel, or methylcellulose).

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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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