A thiazide-like diuretic (water tablet)
Indapamide
A thiazide-like "water tablet" used to lower blood pressure, taken in the morning and usually well tolerated.
What is Indapamide?
Indapamide is a thiazide-like diuretic, sometimes called a 'water tablet', used mainly to lower blood pressure. It is closely related to traditional thiazide diuretics and is a common choice for treating high blood pressure.
Education and reference only. This is a plain-language guide to Indapamide — 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
Indapamide is a thiazide-like diuretic ("water tablet") used mainly to lower blood pressure. It is closely related to traditional thiazide diuretics and is a common first-line choice for high blood pressure, particularly in older people. It gently increases the amount of salt and water the body passes out and relaxes blood vessels, lowering blood pressure over time. It is a long-term, once-daily tablet, available in standard and slow-release (modified-release) forms, and is sold as Natrilix in the UK.
How it works
Indapamide acts on the kidneys to reduce how much salt (sodium) and water they hold on to, so the body sheds a little extra fluid and the volume of blood the heart has to push around falls. Over the longer term it also helps relax and widen blood vessels, which lowers the pressure further. Together these effects bring blood pressure down steadily rather than suddenly, which is why it is used as a regular daily treatment.
Company & origin
Originated / developed by: Servier.
Indapamide, a thiazide-like diuretic, was developed by the French company Servier and introduced in Europe for hypertension around 1974, marketed as Natrilix/Fludex.
What it treats
Conditions Indapamide is used for
Practical use
How to take Indapamide
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Usually taken once a day in the morning, so any extra trips to the toilet happen during the day rather than at night.
- Can be taken with or without food.
- Keep taking it even when you feel well, as high blood pressure usually causes no symptoms.
- Your GP will arrange blood tests to check your kidney function and salt levels.
- Tell your doctor if you feel very thirsty, weak, dizzy or develop muscle cramps.
Weighing it up
Advantages & disadvantages of Indapamide
Advantages
- Effective at lowering blood pressure and reducing cardiovascular risk.
- Taken once daily and inexpensive as a generic.
- Well-established option recommended in UK high blood pressure guidance.
Disadvantages
- Can lower blood levels of salts such as potassium and sodium, which needs monitoring.
- May cause dizziness, tiredness or increased urination.
- Can occasionally raise blood sugar or uric acid levels.
- May not suit people with certain kidney problems.
Practical use
Good to know
It is best taken in the morning, because it increases urine output and an evening dose can mean getting up in the night. It can lower blood levels of potassium and sodium and can nudge up uric acid (which may trigger gout in those prone to it) and blood sugar, so blood tests are checked periodically. The slow-release (modified-release) form is swallowed whole. As with any blood-pressure medicine, it is taken long-term, and dizziness on standing can occur, especially at the start.
Who should not take it / use with caution
- People with significant kidney or liver problems, or with a low blood potassium or sodium level.
- People with gout, used with caution, as it can raise uric acid and trigger an attack.
- Pregnancy, and used with care in people with diabetes or certain heart-rhythm risks.
Monitoring
- Blood pressure
- Kidney function and blood salts (sodium, potassium), and sometimes uric acid and blood sugar
- For dizziness or signs of dehydration
Side effects
- Passing more urine, especially at first, and dizziness or light-headedness on standing.
- Low blood potassium or sodium (which can cause tiredness, cramps or weakness), and a possible rise in uric acid or blood sugar.
- Rarely, a marked drop in blood salts or, very rarely, a serious skin reaction — seek advice for severe weakness, confusion or a widespread rash.
Key interactions
- NSAID painkillers (such as ibuprofen) can reduce its effect and stress the kidneys.
- Care alongside other medicines that lower potassium or affect the heart's rhythm, and with lithium (whose levels it can raise).
- It is often combined with other blood-pressure medicines, but the combination and blood tests are managed together.
Available as: Tablets, including standard and slow-release (modified-release) forms.
Answers
Indapamide: frequently asked questions
Why should I take indapamide in the morning?
Indapamide is a "water tablet" that makes you pass more urine, so taking it in the morning means the extra trips to the toilet happen during the day rather than disturbing your sleep at night. If mornings are difficult, ask your pharmacist about the best routine for you.
How is indapamide different from a "true" thiazide diuretic?
Indapamide is described as "thiazide-like" — it is closely related to classic thiazides such as bendroflumethiazide and works in a very similar way to lower blood pressure, but it has its own profile and is often preferred in current UK guidance. For you as a patient, the practical advice is much the same.
Can indapamide affect my gout or blood sugar?
It can. Indapamide can raise uric acid, which may trigger gout in people prone to it, and can slightly raise blood sugar. This does not happen to everyone, and blood tests help keep an eye on it. Tell your prescriber if you have gout or diabetes so they can monitor or adjust treatment.
Will I need blood tests on indapamide?
Yes, periodically. Because indapamide can change the levels of salts in your blood — especially potassium and sodium — and can affect kidney function, uric acid and blood sugar, your team will check these from time to time, particularly when starting or changing the dose.
What is the difference between indapamide and Natrilix?
They are the same medicine — indapamide is the generic (active-ingredient) name and Natrilix is a UK brand name. Generic indapamide contains the identical active ingredient.
The wider class
About Thiazide-like diuretics
Indapamide belongs to the thiazide-like diuretics class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF: Indapamide.
- electronic Medicines Compendium (SmPC): Natrilix.
- NICE CKS: Indapamide.
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