Can I take Glucomannan and Nexplanon together?
Drug interaction guide
Originally published 25 Jan 2026
Meets Patient’s editorial guidelines
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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
Back to contentsTo 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
Back to contentsSwallowing 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.
Breast cancer
You must not use Nexplanon implant if you have, or have ever had, breast cancer, as the hormones may encourage the growth of certain tumours.
Unexplained vaginal bleeding
If you have vaginal bleeding that has not been explained by a doctor, you must not have the Nexplanon implant inserted until the cause is found.
Diabetes
Glucomannan can significantly lower blood sugar levels. If you are taking medication for diabetes, your dose may need adjustment to prevent hypoglycaemia (low blood sugar).
Liver disease
Do not use Nexplanon if you have severe liver disease or a history of liver tumours, as the implant is processed by the liver.
Food and drink warnings
Back to contentsAlcohol
It is best to avoid or strictly limit alcohol while using hormonal contraceptives. Alcohol can impair your judgement and may increase the risk of side effects like dizziness or nausea.
It is best to avoid or strictly limit alcohol while taking glucomannan. Alcohol can contribute to dehydration, which increases the risk of the supplement causing a blockage in your digestive system.
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
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.
25 Jan 2026 | Originally published

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