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Can I take Glucomannan and Nexplanon together?

Drug interaction guide

Glucomannan is a type of fibre that can slow down or reduce how much of your contraceptive medication is absorbed into your bloodstream. This could potentially make the Nexplanon implant less effective at preventing pregnancy.

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Why this happens

Glucomannan is a highly absorbent fibre that forms a thick gel in the stomach and intestines. This gel can trap other medications (like the hormones released by Nexplanon) or slow down the rate at which they enter the blood. While Nexplanon is an implant, the hormones it releases still circulate through the body and can be affected by changes in gut absorption and 'enterohepatic circulation' (the way hormones are recycled between the liver and the gut).

What you should do

To be safe, you should take glucomannan at least 1 hour after or 4 hours before taking any other oral medications. However, because Nexplanon releases hormones continuously, it is best to speak with your GP or pharmacist before using glucomannan regularly. If you decide to use both, monitor for any breakthrough bleeding or spotting, which could be a sign that hormone levels are fluctuating.

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Important precautions

Swallowing difficulties or inadequate fluid intake

Glucomannan must be taken with at least 1-2 glasses of water. Without enough liquid, it can swell and block your throat or oesophagus, posing a serious choking risk. Do not take this if you have ever had difficulty swallowing.

Use of enzyme-inducing medicines (e.g., St John’s Wort, certain epilepsy or HIV drugs)

Certain medicines and herbal remedies can make the Nexplanon implant significantly less effective, leading to unintended pregnancy. You must use an additional barrier method (like condoms) while taking these medicines and for 28 days after stopping them.

Food and drink warnings

Water / Fluids (General)

You must take glucomannan with plenty of water (at least 1 to 2 glasses) to ensure it reaches your stomach. There is a risk of choking or blockage in the throat or oesophagus if it is swallowed without enough liquid. Do not take it immediately before going to bed.

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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.

  • 24 Jan 2026 | Originally published
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