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Cyclopenthiazide tablets

Clinical author's note Michael Stewart 22/04/2019: Navidrex® and Navispare® tablets have been discontinued in the UK. At the time of review there are no branded or generic products containing cyclopenthiazide available in the UK. Cyclopenthiazide may still be available in other countries. This medicine leaflet is based on medical information available in the UK at the time of writing. Please also refer to the manufacturer's information supplied with your medicine.

Cyclopenthiazide is a 'water tablet' (a diuretic).

It is best taken in the morning.

Any side-effects are usually mild, but may include feeling sick or dizzy.

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About cyclopenthiazide

Type of medicine

A thiazide diuretic

Used for

High blood pressure; fluid retention; heart failure

Also called

Navidrex®; Navispare® (discontinued)

Available as


Cyclopenthiazide belongs to a group of medicines called thiazide diuretics. A diuretic is a medicine which increases the amount of urine that you pass out from your kidneys. They are often referred to as 'water tablets'. Diuretics are a common treatment for high blood pressure (hypertension). They are also used to clear excess fluid from your body in conditions where your body retains more than it needs. This is called oedema. Cyclopenthiazide is also useful in people who have heart failure. Heart failure is a condition where your heart is not functioning as well as it should.

Diuretics like cyclopenthiazide work by interfering with the transport of salt and water across certain cells in your kidneys. The effect of this is to make your kidneys pass out more urine. The removal of fluid reduces your blood pressure and helps reduce the work your heart has to do.

Cyclopenthiazide is usually given alongside other diuretics to treat high blood pressure. When it is used like this, you may be prescribed a combination tablet, such as Navispare®. This brand contains cyclopenthiazide with amiloride. Combination tablets like this help to reduce the number of tablets you need to take each day.

Before taking cyclopenthiazide

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking cyclopenthiazide it is important that your doctor knows:

  • If you are pregnant or breastfeeding.

  • If you have any problems with the way your liver works, or any problems with the way your kidneys work.

  • If you have gout, diabetes or an inflammatory condition called systemic lupus erythematosus (also called lupus, or SLE). These conditions can be made worse by medicines like cyclopenthiazide.

  • If you have been told by a doctor that you have low sodium or potassium levels in your blood, or high calcium levels in your blood.

  • If you have a problem with your adrenal glands, called Addison's disease.

  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

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How to take cyclopenthiazide

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about cyclopenthiazide and will provide you with a full list of the side-effects which you may experience from taking it.

  • Take cyclopenthiazide tablets exactly as your doctor tells you to. The usual dose is ½-1 tablet daily. Your doctor is likely to recommend that you take your dose in the morning. This is so it works during the day and your sleep is not disturbed by you needing to get up to go to the toilet during the night.

  • Swallow the tablet with a drink of water. You can take it either with or without food.

  • If you forget to take a dose, take it as soon as you remember. However, if it is late afternoon when you remember, leave out the forgotten dose and take your next dose as usual on the following day. Do not take two doses on the same day to make up for a missed dose.

Getting the most from your treatment

  • 'Water tablets' (diuretics) like cyclopenthiazide help you to lose water. Occasionally you may lose too much and become lacking in fluid in the body (dehydrated). Let your doctor know if you feel constantly thirsty, your mouth is dry, or your skin looks and feels dry.

  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. The salt balance in your bloodstream may be upset by cyclopenthiazide and your doctor may want you to have a blood test from time to time to check for this.

  • If you have been prescribed cyclopenthiazide for high blood pressure (hypertension), your treatment is likely to be long-term. Although many people with high blood pressure do not feel unwell, if left untreated, high blood pressure can harm your heart and damage your blood vessels. This damage may later result in a heart attack, stroke, or kidney problems, so it is important that you continue to take the tablets regularly to help reduce the risk of this. You may also be given some lifestyle and dietary advice by your doctor, such as stopping smoking, reducing the amount of salt in your diet, eating more fruit and vegetables and less saturated fat, and taking some regular exercise. Following this advice will also help to reduce the risk of damage to your heart and blood vessels.

  • Ask your doctor for advice before drinking alcohol while you are on cyclopenthiazide. Alcohol will add to the blood pressure-lowering effect of cyclopenthiazide which will increase the possibility of you experiencing side-effects such as dizziness.

  • If you buy any medicines, check with a pharmacist that they are suitable to take alongside cyclopenthiazide.

  • If you are due to have an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

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Can cyclopenthiazide cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with cyclopenthiazide. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.


cyclopenthiazide side-effects

What can I do if I experience this?

Feeling sick (nausea), stomach upset

This is usually mild, but it may help to take cyclopenthiazide after food if you are not already doing so

Feeling dizzy, particularly when you stand up (due to low blood pressure)

Getting up more slowly should help. Do not drive and do not use tools or machines while affected

If you experience any other symptoms which you think may be due to the tablets, speak with your doctor or pharmacist for further advice.

How to store cyclopenthiazide

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine, ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article History

The information on this page is written and peer reviewed by qualified clinicians.

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