Moduret 25 tablets contain two active ingredients; amiloride, which is a type of medicine called a potassium-sparing diuretic and hydrochlorothiazide, which is a type of medicine called a thiazide diuretic.

What is it used for?

  • High blood pressure (hypertension).
  • Heart failure.
  • Fluid retention (ascites and oedema) in liver cirrhosis.

How does it work?

  • Moduret 25 tablets contain two active ingredients; amiloride, which is a type of medicine called a potassium-sparing diuretic and hydrochlorothiazide, which is a type of medicine called a thiazide diuretic.
  • Diuretics act in the kidneys. They work by causing the kidneys to increase the amount of salts, such as potassium and sodium, that are filtered out of the blood and into the urine. When these salts are filtered out of the blood by the kidneys, they draw water alongside them. As diuretics increase the removal of salts from the blood, they also cause more water to be drawn out of the blood and into the urine.
  • Removing water from the blood decreases the volume of fluid circulating through the blood vessels.
This subsequently decreases the pressure within the blood vessels. Diuretics such as hydrochlorothiazide and amiloride can therefore be used to lower high blood pressure.
  • Hydrochlorothiazide can cause lots of potassium to be filtered out of the blood, which can sometimes cause the level of potassium in the blood to fall too low. A low blood potassium level is called hypokalaemia and can sometimes be dangerous, particularly for people with heart disease or liver disease.
  • Amiloride on the other hand, is a weaker diuretic that causes potassium to be retained in the body. It is used in combination with the hydrochlorothiazide in this medicine to prevent the amount of potassium in the blood from falling too low.
  • This medicine is used in heart failure, where the pumping mechanism of the heart is less effective. Heart failure can cause fluid to build up in the lungs, causing breathlessness and in the lower limbs, causing swollen ankles. Diuretic medicines are used to remove this excess fluid into the urine. This relieves the symptoms of heart failure and also makes it easier for the heart to pump the blood around the body.
  • This medicine is also used to remove excess fluid that can accumulate in the body in people with cirrhosis of the liver. This fluid may accumulate in the abdomen (ascites) or in the legs (oedema).
  • How do I take it?

    • Moduret 25 tablets can be taken either with or without food.
    • Moduret 25 tablets should be swallowed with a drink of water. The number of tablets to be taken daily will vary depending on your symptoms. The tablets are usually taken once daily, in the morning, but your doctor may advise you to take them in divided doses. Follow the instructions given by your doctor.
    • As diuretics cause your kidneys to produce more urine, you may find that if you take a dose too late in the day that you need to get up in the night to visit the toilet, which is why it is recommended that you take this medicine in the morning. Seek further advice from your doctor or pharmacist.


    • This medicine may cause fatigue and dizziness. You should take care when performing potentially hazardous activities, such as driving or operating machinery, until you know how this medicine affects you and are sure you can perform such activities safely.
    • Alcohol may enhance the blood pressure lowering effect of this medicine, which could cause dizziness or fainting. Take extra care if you drink alcohol while you are taking this medicine.
    • While taking this medicine you may need to have regular blood tests to monitor your kidney function and the levels of salts such as potassium and sodium in your blood.
    • If you experience any of the following symptoms while taking this medicine you should inform your doctor promptly, so that the amount of fluids and salts in your body can be checked: thirst, lethargy, confusion, weakness, drowsiness, muscle cramps, scanty production of urine, abnormal heart rhythm, seizures, nausea and vomiting.
    • This medicine can cause the amount of potassium in your bloodstream to increase. For this reason you should avoid consuming large amounts of foods that have a high potassium content, for example dried fruit, bananas, tomatoes and 'low sodium' salt, while you are taking the medicine. You should also avoid potassium supplements.
    • If you need a test to assess the functioning of your parathyroid gland your doctor may ask you to stop taking this medicine beforehand, as it may interfere with the test results.

    Use with caution in

    • Elderly people.
    • Decreased liver function.
    • Decreased kidney function.
    • Diabetes.
    • People with a high level of uric acid in their blood (hyperuricaemia).
    • Gout.
    • An inflammatory disease of connective tissue (systemic lupus erythematosus).
    • People with high levels of fats (lipids) such as cholesterol and triglycerides in the blood (hyperlipidaemia).

    Not to be used in

    • People whose kidneys are not producing urine.
    • Kidney failure.
    • Diabetic kidney disease (nephropathy).
    • Severe liver disease.
    • People with low levels of consciousness due to cirrhosis of the liver.
    • People allergic to thiazide diuretics.
    • People allergic to medicines from the sulphonamide group, eg the antibiotic sulfamethoxazole.
    • People with a high level of potassium in their blood (hyperkalaemia).
    • People with a high level of calcium in their blood (hypercalcaemia).
    • People with inadequate production of natural steroid hormones by the adrenal glands (Addison's disease).
    • Pregnancy.
    • Breastfeeding.
    • Children or adolescents under 18 years of age.

    This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

    If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

    Pregnancy and breastfeeding

    Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

    • This medicine should not normally be used during pregnancy. Thiazide diuretics can reduce placental blood flow to the baby and, if used in the second or third trimester, can cause problems such as jaundice, low platelet count and disturbances in the baby's electrolyte levels. This medicine should not be used to treat high blood pressure in pregnancy, or to treat fluid retention in otherwise healthy pregnant women. It should only be used in other situations if considered essential by your doctor. The expected benefit to the mother must be greater than the possible risks to the developing baby. Seek further medical advice from your doctor.
    • Hydrochlorothiazide passes into breast milk and could have unwanted effects on a nursing infant. In high doses it can also reduce the production of breast milk. It is not known if amiloride passes into breast milk. This medicine is not recommended for women who are breastfeeding. Seek further medical advice from your doctor.

    Side effects

    Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

    • Headache.
    • Weakness.
    • Loss of appetite.
    • Dizziness.
    • Fatigue.
    • A general feeling of being unwell (malaise).
    • Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting, wind or abdominal pain.
    • Chest pain.
    • Back pain.
    • A drop in blood pressure that occurs when going from lying down to sitting or standing, which results in dizziness and lightheadedness (postural hypotension).
    • Abnormal heart beats (arrhythmias).
    • Skin reactions such as rash, itching, flushing, sweating.
    • Muscle cramps.
    • Difficulty sleeping (insomnia).
    • Confusion.
    • Nervousness.
    • Restlessness.
    • Sensation of pins and needles.
    • Spinning sensation (vertigo).
    • Shortness of breath.
    • Increased level of potassium in the blood (hyperkalaemia).
    • Decreased level of sodium in the blood (hyponatraemia).
    • Raised level of uric acid in the blood (hyperuricaemia), which can cause kidney problems and gout.
    • Raised levels of fats such as cholesterol in the blood.
    • Decreased sex drive and erectile dysfunction (impotence).
    • Increased need to pass urine.
    • Problems with kidney function.

    The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

    For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

    How can this medicine affect other medicines?

    It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.

    This medicine is likely to have an additive effect with other medicines that decrease blood pressure, particularly medicines that are used to treat high blood pressure (antihypertensives). This may cause dizziness, which can usually be relieved by lying down until the symptoms pass. If you feel dizzy while taking this medicine in combination with other medicines that can lower blood pressure you should let your doctor know, as your doses may need adjusting. Other medicines that decrease blood pressure include the following:

    • ACE inhibitors, eg enalapril
    • aldesleukin
    • alpha-blockers such as prazosin
    • alprostadil
    • angiotensin II receptor antagonists such as losartan
    • antipsychotics such as chlorpromazine
    • benzodiazepines, eg temazepam, diazepam
    • baclofen
    • beta-blockers such as propranolol
    • calcium-channel blockers such as verapamil, nifedipine
    • clonidine
    • diazoxide
    • other diuretics, eg furosemide (if this medicine is used with other diuretics there may also be a greater chance of the level of sodium or potassium in your blood falling too low)
    • dopamine agonists, eg bromocriptine, apomorphine
    • hydralazine
    • levodopa
    • MAOI antidepressants, eg phenelzine
    • methyldopa
    • minoxidil
    • moxisylyte
    • moxonidine
    • nicorandil
    • nitrates, eg glyceryl trinitrate
    • tizanidine.

    Since amiloride can raise the level of potassium in the blood, Moduret tablets should not be used in combination with other potassium-sparing diuretics, eg spironolactone, eplerenone, triamterene, or with potassium supplements, as this can cause the level of potassium in the blood to rise too high. The following medicines can also raise the level of potassium in the blood and if you take any of these with Moduret the level of potassium in your blood should be regularly monitored:

    • ACE inhibitors, eg captopril
    • aliskiren
    • angiotensin-II receptor antagonists, eg losartan
    • ciclosporin
    • co-trimoxazole
    • drospirenone
    • non-steroidal anti-inflammatory drugs (NSAIDs) such as indometacin
    • potassium-containing salt substitutes, eg Lo-salt
    • potassium salts, eg potassium citrate for cystitis
    • tacrolimus
    • trilostane
    • trimethoprim.

    Hydrochlorothiazide can decrease the amount of potassium in the blood. If Moduret tablets are used in combination with any of the following medicines, which can also lower potassium in the blood, the level of potassium in your blood could fall too low (hypokalaemia):

    • acetazolamide
    • amphotericin
    • corticosteroids, such as hydrocortisone and prednisolone
    • beta 2 agonists, eg salbutamol, terbutaline
    • other diuretics, eg furosemide
    • theophylline.

    Diuretics can sometimes increase blood glucose levels and people with diabetes may therefore need increases in their dose of insulin or antidiabetic tablets while taking this medicine. If you have diabetes you should talk to your doctor about this. You may need to monitor your blood sugar levels more frequently.

    Hydrochlorothiazide can increase the amount of calcium in your blood. If you are taking calcium or vitamin D supplements, or regularly take large amounts of calcium-containing antacids, your doctor may want to monitor the level of calcium in your blood to make sure it doesn't rise too high. Taking occasional antacids with Moduret should not cause any problems.

    This medicine can reduce the ability of the body to remove the medicine lithium, which can cause the level of lithium in the blood to rise too high. If you are taking lithium your lithium level should be checked after you start and stop treatment with this medicine, as well as after any dose changes. Your lithium dose may need adjusting.

    Colestyramine and colestipol can reduce the absorption of hydrochlorothiazide from the gut. If you have been prescribed either of these medicines you should not take them within four hours of taking Moduret.

    There may be an increased risk of allergic reactions to allopurinol in people taking thiazide diuretics such as hydrochlorothiazide, particularly if they also have any kidney problems.

    The following medicines may reduce the diuretic and blood pressure lowering effect of this medicine:

    • corticosteroids, such as dexamethasone or prednisolone
    • oestrogens, such as those in the contraceptive pill
    • regular use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, diclofenac or indomethacin (occasional painkilling doses are unlikely to have a significant effect). Diuretics such as this one also increase the chance of side effects on the kidneys that can be caused by NSAIDs.