Valsartan/Hydrochlorothiazide tablets contain two active ingredients, valsartan and hydrochlorothiazide. Tablets containing valsartan and hydrochlorothiazide are also available without a brand name, ie as the generic medicine.

What is it used for?

  • High blood pressure with no known cause (essential hypertension).

How does it work?

  • Co-diovan tablets contain two active ingredients, valsartan and hydrochlorothiazide. Tablets containing valsartan and hydrochlorothiazide are also available without a brand name, ie as the generic medicine.
  • Hydrochlorothiazide is a type of medicine called a thiazide diuretic. Thiazide diuretics act in the kidneys, where they increase the production of urine.
  • 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, water is drawn alongside them.
As hydrochlorothiazide increases the removal of salts from the blood, it also causes 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. The drop in fluid volume results in a drop in the pressure of the fluid within the blood vessels, which helps to lower high blood pressure. It also decreases the effort required by the heart to pump blood around the body.
  • Valsartan is a type of medicine called an angiotensin II antagonist. It works by blocking receptors in the body known as angiotensin II receptors. This prevents the action of a hormone called angiotensin II.
  • Angiotensin II is produced naturally by the body and plays an important part in regulating blood pressure and fluid balance. It has two main actions. It causes the blood vessels to narrow and the kidneys to retain salt and water.
  • As valsartan blocks angiotensin II receptors, it prevents the actions of angiotensin II, causing its effects to be reversed. As a result, the blood vessels widen and the amount of fluid removed from the blood by the kidneys is increased. This decreases the amount of fluid in the blood vessels, which lessens the resistance and pressure in the blood vessels. The overall effect of this is a reduction in blood pressure.
  • Valsartan and hydrochlorothiazide have an additive effect on lowering blood pressure. This combination medicine is used to treat high blood pressure in people whose blood pressure is not adequately controlled with just valsartan.
  • How do I take it?

    • The strength of Co-Diovan tablets that are prescribed depends on how well your blood pressure is controlled. The tablets are taken once a day. You should try to always take your dose at the same time of day, usually in the morning.
    • The tablets can be taken either with or without food. They should be swallowed with a drink of water.
    • If you forget to take a dose of this medicine take it as soon as you remember, unless it is nearly time for your next dose. In this case leave out the forgotten dose and just take your next dose as usual. Do not take a double dose to make up for a missed dose.
    • You will usually need to keep taking this medicine long-term to help control your blood pressure. Do not stop taking this medicine unless your doctor tells you to.


    • Dizziness and weariness may occasionally occur during treatment with blood pressure lowering medicines. This may be made worse by drinking alcohol. If you are affected, caution is required when driving or operating machinery.
    • Your blood pressure and kidney function should be regularly monitored while you are taking this medicine.
    • It is recommended that the levels of salts (electrolytes such as potassium and sodium) in your blood should be monitored while you are taking this medicine. If you experience any of the following symptoms you should inform your doctor promptly, so that the amount of fluids and salts in your body can be checked: feeling unusually thirsty, lethargic, confused, weak, or drowsy, muscle cramps, scanty production of urine, dry mouth, abnormal heart rhythm, feeling sick or vomiting.
    • 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.

    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 be used in pregnancy, particularly in the second and third trimesters, as it may be harmful to the unborn baby. Seek further medical advice from your doctor. If you get pregnant while taking this medicine, stop taking it and consult your doctor immediately.
    • It is not known if valsartan passes into breast milk, however hydrochlorothiazide does pass into breast milk. It may also decrease the production of breast milk. This medicine should therefore not be used during breastfeeding. Mothers will need to either stop breastfeeding while taking this medicine, or not take this medicine. This will depend on how important the medicine is for treating the mother’s blood pressure. It is important to seek 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.


    • Fatigue.
    • Blurred vision.
    • Dehydration.
    • Pins and needles sensation.
    • Sensation of ringing or other noise in the ears (tinnitus).
    • Spinning sensation.
    • Abdominal pain.
    • Cough.
    • Pain in the muscles.
    • Low blood pressure.

    Very rare 

    • Dizziness.
    • Diarrhoea.
    • Pain in the joints.

    Frequency unknown

    • Fainting.
    • Decreased kidney function or kidney failure.
    • Increased level of uric acid in the blood.
    • Decreased level of sodium in the blood.
    • Increased or decreased level of potassium in the blood.
    • Severe swelling of lips, face or tongue (angioedema). If you experience this you should consult a doctor immediately. Treatment with this medicine should be stopped and not restarted.
    • Decrease in the number of platelets in the blood (thrombocytopenia).
    • Decrease in the number of a type of white blood cell (neutrophil) in the blood (neutropenia).
    • Skin reactions, such as rash and itching.

    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.

    If this medicine is used in combination with other medicines that lower blood pressure, either to treat high blood pressure (antihypertensives), or as a side effect, the combination might lower your blood pressure too much. This could make you feel dizzy or faint, particularly when moving from a lying or sitting position to sitting or standing. If this happens to you, you should sit or lie down until the symptoms pass. This is more likely to happen when you first start taking this medicine, particularly if you have been taking a high dose of a diuretic. Tell your doctor if any dizziness persists, as your medicine doses may need adjusting. Other medicines that decrease blood pressure include the following:

    • ACE inhibitors, eg enalapril
    • aldesleukin
    • alpha-blockers such as prazosin
    • alprostadil
    • other 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
    • diuretics, eg furosemide, bendroflumethiazide
    • dopamine agonists, eg bromocriptine, apomorphine
    • hydralazine
    • levodopa
    • MAOI antidepressants, eg phenelzine
    • methyldopa
    • minoxidil
    • moxonidine
    • moxisylyte
    • nicorandil
    • nitrates, eg glyceryl trinitrate
    • sildenafil
    • tizanidine.

    Both valsartan and hydrochlorothiazide may increase the blood level of the medicine lithium, and this medicine is therefore not recommended for people taking lithium. If it is necessary to take lithium with this medicine, your doctor should carefully monitor your blood level of lithium. You should let your doctor know if you experience any signs that your lithium level is increasing, for example, loss of appetite, diarrhoea, vomiting, blurred vision, muscle weakness, lack of co-ordination, drowsiness, tremor, unsteadiness, muscle twitching, ringing in the ears or confusion.

    Valsartan may increase the level of potassium in your blood. If this medicine is taken with other medicines that can increase blood potassium levels, this effect may be enhanced. Such medicines include those listed below:

    • ACE inhibitors, eg captopril, enalapril
    • ciclosporin
    • drospirenone
    • heparin
    • non-steroidal anti-inflammatory drugs, eg indometacin, diclofenac, ibuprofen, naproxen
    • potassium-sparing diuretics eg spironolactone, triamterene, amiloride
    • potassium supplements
    • potassium salts, eg potassium citrate for cystitis
    • potassium-containing salt substitutes such as Lo-Salt
    • tacrolimus
    • trimethoprim.

    Hydrochlorothiazide can decrease the level of potassium in your blood. If this medicine is taken with other medicines which can lower blood potassium levels, this effect may be enhanced. Such medicines include the following:

    • amphotericin
    • beta agonist bronchodilators such as salbutamol or salmeterol
    • carbenoxolone
    • corticosteroids such as dexamethasone or prednisolone
    • other diuretics such as bendroflumethiazide or furosemide
    • stimulant laxatives, eg senna
    • theophylline.

    If you are taking any of these medicines that could affect your potassium level, your potassium level should be monitored. This is particularly important if you are also taking digoxin or a medicine for abnormal heart beats.

    Hydrochlorothiazide may raise blood glucose levels. People with diabetes should therefore carefully monitor their blood sugar while taking this medicine, as the effectiveness of antidiabetic medicines may be reduced. This effect may be enhanced if you are also taking diazoxide. Dose adjustments of your antidiabetic medicine may be required. Discuss this with your doctor.

    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 while you are taking Co-diovan. Taking occasional antacids should not cause any problems.

    Hydrochlorothiazide may also raise uric acid levels. People with gout may therefore need adjustments to the doses of their gout medicines to keep them effective.

    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 Co-diovan.

    The following medicines may oppose the 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).

    Non-steroidal anti-inflammatory drugs (NSAIDs, eg indomethacin, diclofenac, ibuprofen, naproxen) may also increase the risk of raised blood potassium and kidney problems when used in combination with this medicine. They should be used with caution in people taking this medicine, particularly elderly people. Always get advice from your doctor or pharmacist before taking this type of painkiller. Your doctor may want to monitor your kidney function.

    If you have any more questions please ask your Pharmacist.

    Remember to keep all medicines out of reach of children
    Please Note: We have made every effort to ensure that the content of this information sheet is correct at time of publish, but remember that information about drugs may change. This sheet does not list all the uses and side-effects associated with this drug. For full details please see the drug information leaflet which comes with your medicine. Your doctor will assess your medical circumstances and draw your attention to any information or side-effects which may be relevant in your particular.



    Health Reference: Hypertension