A gut-acting medicine for IBS with constipation
Tenapanor
A gut-acting medicine for irritable bowel syndrome with constipation, also used to lower phosphate in kidney disease, taken before meals.
What is Tenapanor?
Tenapanor is a medicine that works in the gut. It is used for irritable bowel syndrome with constipation (IBS-C), where it helps soften stools, ease bloating and discomfort and improve bowel movements, and it is also used to help lower high phosphate levels in some people with kidney disease. It works only in the gut and is barely absorbed into the body. The most common and important side effect is diarrhoea, which can sometimes be severe. It is taken before meals, is not for children, and should be stopped and reviewed if diarrhoea becomes troublesome.
Education and reference only. This is a plain-language guide to Tenapanor — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Tenapanor is a medicine that acts within the gut rather than being absorbed into the bloodstream. It has two main uses: treating irritable bowel syndrome with constipation (IBS-C), where bowel movements are infrequent and stools are hard, with bloating and tummy discomfort; and helping to lower high phosphate levels in some people with chronic kidney disease, particularly those on dialysis. It is taken by mouth, usually before meals, and works locally in the gut, which is why very little of it gets into the rest of the body.
How it works
Tenapanor blocks a transporter in the gut lining that normally moves sodium (salt) from the gut into the body. By reducing how much sodium is absorbed, it keeps more water in the bowel, which softens the stool and helps it move along, easing constipation in IBS. The same action also reduces how much phosphate the gut absorbs from food, which is why it can help lower high phosphate levels in kidney disease. Because it works locally and is barely absorbed, its effects and side effects are mostly centred on the gut, the main one being diarrhoea.
Company & origin
Originated / developed by: Specialist manufacturer.
A medicine used in the UK for irritable bowel syndrome with constipation, and to help lower phosphate in some people with kidney disease, working within the gut.
What it treats
Conditions Tenapanor is used for
Practical use
How to take Tenapanor
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth before meals, as advised, so it works as intended.
- Expect that it may cause looser stools, and report diarrhoea that becomes frequent, watery or severe.
- Keep up your fluids, and seek advice promptly if you feel dizzy, very thirsty or are passing little urine.
- Do not give it to children, in whom there is a risk of serious dehydration.
- Tell your prescriber about your other medicines, and follow advice on spacing them where needed.
Weighing it up
Advantages & disadvantages of Tenapanor
Advantages
- Eases irritable bowel syndrome with constipation by softening stools and improving bowel movements.
- Also helps lower high phosphate levels in some people with kidney disease.
- Works locally in the gut and is barely absorbed, so it lacks many body-wide effects.
Disadvantages
- Commonly causes diarrhoea, which can sometimes be severe and lead to dehydration.
- Must be taken before meals, so timing matters.
- Not suitable for children because of the risk of serious dehydration.
Practical use
Good to know
The most important thing to expect with tenapanor is diarrhoea, which is common and can occasionally be severe and lead to dehydration; if diarrhoea becomes troublesome, the medicine should be paused and the situation reviewed rather than pushed through. It is taken before meals, so getting the timing right matters for how well it works. It is not suitable for children, in whom there is a particular concern about serious dehydration. It works only in the gut and is hardly absorbed, so it does not have the wider body-wide effects of many medicines. Tell your prescriber about other medicines, as good timing helps avoid interactions, and report severe or watery diarrhoea, especially with dizziness or reduced urination, which can signal dehydration.
Who should not take it / use with caution
- Children must not take it, because of the risk of serious dehydration.
- People who have a known or suspected bowel blockage should not take it.
- People who have had a serious allergic reaction to tenapanor should not take it, and it is used with care in those prone to dehydration.
Monitoring
- Reviewing how bowel symptoms or phosphate levels respond to treatment.
- Watching for diarrhoea and signs of dehydration.
- Checking blood tests, including phosphate, where it is used for kidney disease.
Side effects
- Diarrhoea, which is common and can sometimes be severe.
- Bloating, wind or tummy discomfort.
- Less commonly, dehydration if diarrhoea is severe, with dizziness or reduced urination.
Key interactions
- Diarrhoea can affect how well some other medicines are absorbed, so report troublesome symptoms.
- Spacing may be advised for medicines whose absorption depends on a steady gut, on your prescriber's advice.
- Tell your team about all your medicines, including other treatments for the bowel or for phosphate.
Available as: Tablets taken by mouth, usually before meals.
Answers
Tenapanor: frequently asked questions
What is tenapanor used for?
It is used for irritable bowel syndrome with constipation, and to help lower high phosphate levels in some people with kidney disease, working within the gut.
Why does it cause diarrhoea?
It keeps more water in the bowel to soften stools, so looser stools are expected; diarrhoea is the most common side effect and can sometimes be severe.
When should I take it?
It is taken before meals, as advised, which helps it work as intended.
Can children take it?
No. It is not suitable for children, in whom there is a particular risk of serious dehydration.
What should I do if the diarrhoea is bad?
Pause the medicine and seek advice rather than carrying on, especially if you feel dizzy, very thirsty or are passing little urine, as this can mean dehydration.
Authoritative sources
- BNF
- NICE CKS
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