Tiaziddiuretika
Granskad av Dr Surangi Mendis, MRCGPSenast uppdaterad av Dr Rachel Hudson, MRCGPSenast uppdaterad 1 Nov 2023
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Tiaziddiuretika används främst för att behandla högt blodtryck (hypertoni). De används ibland också för hjärtsvikt.
Överblick
Thiazide diuretics are a type of medicine, sometimes called 'water tablets', that increase urine production.
They are commonly used to treat high blood pressure and can also help clear excess fluid from the body.
Thiazide diuretics work by making kidneys pass out more fluid and by widening blood vessels.
Side-effects are uncommon but can include changes in blood sugar, uric acid, or salt levels.
Most thiazide diuretics are taken once a day in the morning.
You can report possible side-effects to medicines using the Yellow Card Scheme.

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What are thiazide diuretics?
A diuretic is a medicine which increases the amount of water that you pass out from your kidneys. A diuretic causes an increase in urine, called a diuresis. So, they are sometimes called 'water tablets'. There are different types of diuretics which work in different ways and thiazide diuretics are one type of diuretic.
Thiazide diuretics are a common treatment for högt blodtryck (hypertoni). They are also occasionally used to clear fluid from the body in conditions where your body accumulates too much fluid, such as hjärtsvikt. However, a different type of diuretic called a loop diuretic is more commonly used to treat heart failure.
Thiazide diuretic examples
There are a number of thiazide diuretics - they include:
Each drug has a number of different brand names.
How thiazide diuretics work
One of their effects is to make the kidneys pass out more fluid. They do this by interfering with the transport of salt and water across certain cells in the kidneys.
Thiazide diuretics tend to have only a weak action on the kidneys so you don't notice a great increase in urine if you take these (compared with loop diuretics).
They also have the effect of widening (dilating) blood vessels. A combination of these two effects reduces the blood pressure.
Thiazide diuretics side-effects
Side-effects are uncommon, as the dose needed to lower blood pressure is low. The leaflet which comes in the tablet packet provides a full list of possible side-effects. So, it is important to read that leaflet if you are prescribed a thiazide diuretic.
Common or serious possible side-effects include:
A possible increase in your blood sugar level. Some people with diabetes may need more treatment to keep the blood sugar level normal.
A possible increase in the level of uric acid. So, if you have gout, you may have more gout attacks. A first attack of gout is sometimes triggered by taking a diuretic.
The salt balance in the bloodstream is sometimes upset which can cause a low blood level of potassium, sodium and magnesium, and a high level of calcium. These effects may cause weakness, confusion and, rarely, abnormal heart rhythms to develop. You may be advised to have a blood test to check for these problems.
Other problems, such as:
Upset stomach.
Dizziness on standing - due to too lågt blodtryck (hypotoni).
Erection problems (impotence) - often reversible on stopping treatment.
Skin sensitivity to sunlight.

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Other considerations
Most thiazide diuretics are taken once a day in the morning. Any reduction in blood pressure is maintained throughout the 24 hours by this once-a-day dose. However, the effect of passing extra urine wears off within 12 hours.
So, you will not have to get up in the night to make extra trips to the toilet. Indeed, the dose used to treat high blood pressure (hypertension) is quite low, and many people barely notice an increase in the amount of urine that they pass.
Patientval för Heart and blood medicines

Behandling och medicinering
Medicin mot högt blodtryck
For detailed information about your own medication you should read the leaflet that comes inside the medicine packet.
av Dr Philippa Vincent, MRCGP

Behandling och medicinering
Aspirin och andra blodförtunnande läkemedel
Most people who have a cardiovascular disease (for example, angina, peripheral arterial disease, or a previous heart attack, transient ischaemic attack (TIA) or stroke) take a low-dose aspirin (75 mg) each day or clopidogrel (75 mg) each day. This reduces the risk of heart attack by about a third. It reduces the risk of having a stroke by about a quarter. A daily low dose of aspirin also reduces the risk of developing a number of common cancers, but it is not advised that everyone in the population should take aspirin for this reason. This is because in some people aspirin can increase the risk of stomach bleeding and stomach ulcers, which are sometimes fatal.
av Dr Toni Hazell, MRCGP
Vanliga frågor
When is the best time of day to take a thiazide diuretic?
Most thiazide diuretics are typically taken once a day in the morning. This schedule ensures that any effects of passing extra urine wear off within 12 hours, meaning you shouldn't have to get up during the night for additional toilet trips.
Will taking a thiazide diuretic make me need to use the toilet frequently?
While thiazide diuretics do increase urine output, the dose used for high blood pressure is generally low. Many people find they barely notice an increase in the amount of urine they pass. The effect of passing extra urine also wears off within 12 hours, so it's unlikely to cause frequent night-time toilet visits.
Can thiazide diuretics affect my blood test results?
Yes, thiazide diuretics can sometimes cause an upset in the salt balance in your bloodstream. This may lead to lower levels of potassium, sodium, and magnesium, and higher levels of calcium. Your doctor may advise you to have a blood test to monitor these levels if you are taking this medication.
Can taking a thiazide diuretic make me feel dizzy?
A possible side-effect of thiazide diuretics is dizziness, particularly when standing up. This can occur if your blood pressure becomes too low (hypotension) due to the medication.
Vidare läsning och referenser
- Hypertension in adults: diagnosis and management; NICE (August 2019 - last updated November 2023)
- Burnier M, Bakris G, Williams B; Redefining diuretics use in hypertension: why select a thiazide-like diuretic? J Hypertens. 2019 Aug;37(8):1574-1586. doi: 10.1097/HJH.0000000000002088.
- Pham D, Grodin JL; Dilemmas in the Dosing of Heart Failure Drugs: Titrating Diuretics in Chronic Heart Failure. Card Fail Rev. 2017 Nov;3(2):108-112. doi: 10.15420/cfr.2017:10:1.
Om författarenVisa fullständig biografi

Dr Rachel Hudson, MRCGP
Allmänläkare och medicinsk författare
MBChB, MRCGP (2008), BSc (Medical Science), DFSRH, DRCOG, DCH
Dr Rachel Hudson är en NHS-läkare som arbetar i nordvästra England.
Om recensentenVisa fullständig biografi

Dr Surangi Mendis, MRCGP
Consultant and Medical Author
MBBS, BSc (1st), MRCGP (2014), DFSRH, PGcert otology and audiology
Surangi Mendis is a consultant in Audiovestibular Medicine and Neuro-otology at The Royal National ENT and Eastman Dental Hospitals, UCLH.
Artikelhistorik
Informationen på denna sida är skriven och granskad av kvalificerade kliniker.
Artikeln finns också på Engelska, Tyska, Spanska, Franska, Italienska, Portugisiska, Hindi, Hebreiska, Arabiska, och Svenska.
Next review due: 30 Oct 2028
1 Nov 2023 | Senaste versionen

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