Triamterene capsules

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Triamterene is a 'water' tablet (diuretic) - it will make you want to go to the toilet more often to pass urine.

It may cause your urine to look slightly blue in some lights - this is harmless.

Any side-effects are usually mild.
Type of medicineA potassium-sparing diuretic
Used forWater retention (oedema)
Available asCapsules

Triamterene belongs to the group of medicines known as potassium-sparing 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. Triamterene is called a potassium-sparing diuretic because, unlike some other diuretics, it does not cause your body to lose potassium. It is used to treat water retention (oedema), and it is also given alongside other diuretics to reduce the amount of potassium they cause your body to loose.

Oedema occurs when fluid leaks out of your blood vessels, causing swelling in the tissues of your lungs, feet or ankles. This makes you feel breathless and your legs feel puffy. It is commonly caused by heart failure or liver disease. Triamterene prevents the build-up of this fluid by increasing the amount of urine your kidneys produce.

Triamterene can be prescribed as a treatment on its own, or alongside other diuretics. When it is used with other diuretics, it can be prescribed as a combination tablet to help cut down on the number of tablets you need to take each day. Combination tablets include Frusene® (triamterene with furosemide), Kalspare® (triamterene with chlortalidone) and a combination called co-triamterzide (triamterene with hydrochlorothiazide), which has the brand name Dyazide®.

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 triamterene it is important that your doctor knows:

  • If you are pregnant or breast-feeding.
  • If you have problems with the way your kidneys work, or any difficulty passing urine.
  • If you have any problems with the way your liver works.
  • If you have sugar diabetes.
  • If you have attacks of gout.
  • If you have been told by a doctor that you have high levels of potassium in your blood.
  • If you have a problem with your adrenal glands, called Addison's disease.
  • If you are taking any other medicines. This includes any medicines 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.
  • Before you start the treatment, read the manufacturer's printed information leaflet from inside your pack. It will give you more information about triamterene and will also provide you with a full list of side-effects which you could experience from taking it.
  • Take triamterene exactly as your doctor tells you to. It is usual, to begin with, to take 3-5 capsules a day divided into two doses, one dose with your breakfast and the other at lunchtime. After the first week or so, your doctor is likely to ask you to take the capsules on alternate days only. The directions for taking your doses will be printed on the label of the pack to remind you about what the doctor said to you.
  • Diuretics are best taken no later than mid-afternoon. This is because you will find you may need to go to the toilet a couple of times after taking it and this will disturb your sleep if you take it too late in the day.
  • Swallow the capsules with a drink of water. You can take triamterene either with or without food.
  • If you forget to take a dose of triamterene, take it when you remember if it is only a few hours late. If it is after mid-afternoon, leave out the forgotten dose completely and take your next dose when it is due. Do not take two doses at the same time to make up for a missed dose.
  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. The balance of salts in your blood may be upset by triamterene so your doctor may want you to have a blood test from time to time to check for this.
  • Diuretics help you to lose water, so you can breathe and move more easily. If, however, you lose too much fluid, you may become lacking in fluid in the body (dehydrated). This will make you feel thirsty and make your skin look and feel dry. Let your doctor know if this happens, as your dose may need to be adjusted.
  • Because triamterene is a potassium-sparing diuretic, you should try to avoid things with a high potassium content, such as 'salt substitutes'. This is so the level of potassium in your body does not become too high.
  • Treatment with diuretics is usually long-term, so continue to take triamterene unless your doctor advises you otherwise.
  • If you buy any medicines 'over the counter', please check with a pharmacist that they are suitable for you to take alongside your prescribed medicines.
  • Triamterene can cause your urine to look slightly blue in some lights - this is harmless and nothing to be concerned about.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the common ones associated with triamterene. 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.

Common triamterene side-effects (these affect less than 1 in 10 people)
What can I do if I experience this?
Feeling or being sickStick to simple foods - avoid fatty or spicy meals. Try taking the capsules after a meal or a snack
DiarrhoeaDrink plenty of water to replace the lost fluids
Changes to the results of some blood testsYour doctor will check for this from time to time

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

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

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. 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.

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

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.

Further reading & references

  • Manufacturer's PIL, Triamterene 50 mg Capsules; Amdipharm Mercury Company Limited, The electronic Medicines Compendium. Dated December 2013.
  • British National Formulary; 71st Edition (Mar-Sep 2016) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr Helen Huins
Document ID:
3202 (v24)
Last Checked:
Next Review:
The Information Standard - certified member

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