Co-Diovan

Managing high blood pressure often requires more than one medicine, particularly when a single agent does not bring readings to an adequate level. Co-Diovan is a branded prescription combination tablet containing valsartan, an angiotensin receptor blocker (ARB), and hydrochlorothiazide, a thiazide diuretic. It is licensed for the treatment of hypertension in adults whose blood pressure is not adequately controlled on either valsartan or hydrochlorothiazide alone. By combining two complementary antihypertensive mechanisms in a single once-daily tablet, Co-Diovan simplifies treatment and supports medication adherence in patients who require combination therapy. A prescription can only be issued following a clinical consultation with a registered prescriber.

Co-Diovan is a branded combination prescription medicine manufactured by Novartis Pharmaceuticals UK Ltd. Each film-coated tablet contains two active ingredients: valsartan and hydrochlorothiazide. Valsartan is an angiotensin II receptor blocker (ARB) that relaxes blood vessels. Hydrochlorothiazide is a thiazide diuretic that reduces fluid volume in the bloodstream. Together they provide complementary blood pressure-lowering effects through two different mechanisms.

Co-Diovan is licensed in the United Kingdom for the treatment of essential hypertension in adults. It is indicated for patients whose blood pressure is not adequately controlled on monotherapy with either valsartan or hydrochlorothiazide alone and for patients being switched from taking separate valsartan and hydrochlorothiazide tablets at equivalent doses. It is available in three strengths: 80mg/12.5mg, 160mg/12.5mg, and 160mg/25mg, where the first figure represents the valsartan dose and the second the hydrochlorothiazide dose.

All clinical information on this page is drawn from the current UK Summary of Product Characteristics for Co-Diovan film-coated tablets.

Important: Co-Diovan must not be used during pregnancy. Both valsartan (an ARB) and hydrochlorothiazide carry significant risks to the developing foetus. ARBs can cause serious foetal kidney damage, reduced amniotic fluid, and skull abnormalities, particularly during the second and third trimesters. If you become pregnant while taking Co-Diovan, stop the medicine immediately and contact your prescriber. Effective contraception is essential for women of childbearing potential during treatment.

Co-Diovan lowers blood pressure through the combined actions of its two active ingredients, which work by different and complementary mechanisms.

Valsartan: ARB Action

Valsartan blocks the AT1 angiotensin II receptor. Angiotensin II is a hormone that causes blood vessels to constrict and promotes the retention of sodium and water by stimulating aldosterone release. By blocking the receptor at which angiotensin II acts, valsartan prevents these effects. Blood vessels relax and widen, reducing the resistance the heart must overcome to pump blood, and blood pressure falls. Unlike ACE inhibitors, valsartan does not cause a build-up of bradykinin and is therefore much less likely to cause a persistent dry cough.

Hydrochlorothiazide: Thiazide Diuretic Action

Hydrochlorothiazide acts on the distal convoluted tubule of the kidney, where it inhibits the sodium and chloride co-transporter. This reduces the reabsorption of sodium and chloride, which increases the amount of sodium and water excreted in urine. The resulting reduction in blood volume lowers blood pressure. Hydrochlorothiazide also reduces peripheral vascular resistance with continued use.

Combined Antihypertensive Effect

Valsartan and hydrochlorothiazide lower blood pressure by different mechanisms, and their effects are additive when used together. The vasodilatory action of valsartan complements the volume-reducing action of hydrochlorothiazide. In addition, valsartan partially offsets the potassium loss and renin-angiotensin-aldosterone system activation that hydrochlorothiazide can cause, making the combination more metabolically balanced than hydrochlorothiazide alone. The combined effect in a single once-daily tablet provides sustained blood pressure control over 24 hours.

Always take Co-Diovan exactly as your prescriber instructs. The information below summarises key points from the current UK SmPC. Read the Patient Information Leaflet supplied with your medicine before starting treatment.

• Take Co-Diovan once daily, at the same time each day.
• Co-Diovan can be taken with or without food.
• Swallow the tablet whole with a glass of water. Do not crush or chew.
• If you miss a dose, take it as soon as you remember on the same day. If you only remember the following day, skip the missed dose and continue with your normal schedule. Do not take two doses on the same day.
• Do not stop taking Co-Diovan without speaking to your prescriber first. Stopping combination antihypertensive treatment suddenly may cause your blood pressure to rise.
• Attend all blood test and monitoring appointments arranged by your prescriber. Co-Diovan affects electrolyte levels and kidney function, and these require periodic review during treatment.

Co-Diovan is available in three fixed-dose combination strengths through this service. The dose of each active ingredient is expressed as valsartan/hydrochlorothiazide. The appropriate strength will be determined by your prescriber based on your blood pressure, previous monotherapy response, kidney function, and clinical history.

Co-Diovan 80mg/12.5mg Tablets

Each tablet contains 80mg of valsartan and 12.5mg of hydrochlorothiazide. This is the lowest dose combination and is used as a starting point in patients switching from monotherapy with either valsartan 80mg or hydrochlorothiazide 12.5mg whose blood pressure requires additional control. It may also be used in patients who are sensitive to antihypertensive medicines, including older patients. Your prescriber will advise whether this strength is appropriate for your circumstances.

Co-Diovan 160mg/12.5mg Tablets

Each tablet contains 160mg of valsartan and 12.5mg of hydrochlorothiazide. This strength is appropriate for patients whose blood pressure is inadequately controlled on valsartan 160mg monotherapy and in whom the addition of a low dose of hydrochlorothiazide is clinically indicated. It is also used for patients who have previously taken separate valsartan 160mg and hydrochlorothiazide 12.5mg tablets.

Co-Diovan 160mg/25mg Tablets

Each tablet contains 160mg of valsartan and 25mg of hydrochlorothiazide. This is the highest dose combination available and is used in patients requiring a greater antihypertensive effect than the 160mg/12.5mg combination provides. It corresponds to the combination of valsartan 160mg and hydrochlorothiazide 25mg taken as separate tablets. All dose decisions are made by your prescriber. Do not increase your strength without medical advice.

Like all medicines, Co-Diovan can cause side effects. Because it contains two active ingredients, it carries the potential side effects of both valsartan and hydrochlorothiazide. The information below is based on the current UK SmPC. Refer to the Patient Information Leaflet for the full list.

Common Side Effects (may affect up to 1 in 10 people)

• Dizziness or lightheadedness, particularly when standing up quickly (postural hypotension).
• Headache.
• Raised blood potassium levels (hyperkalaemia), particularly in patients with kidney impairment or those taking other medicines that raise potassium. This is an effect of the valsartan component.
• Low potassium levels (hypokalaemia), which can be caused by the hydrochlorothiazide component, particularly at higher doses. Symptoms include muscle cramps, weakness, and an irregular heartbeat.
• Low sodium levels (hyponatraemia), which may cause fatigue, confusion, or nausea.
• Raised blood uric acid levels, which can trigger or worsen gout in susceptible patients.

Uncommon Side Effects (may affect up to 1 in 100 people)

• Impaired kidney function, particularly in patients with pre-existing kidney disease or renal artery stenosis.
• Low blood pressure, particularly in patients who are dehydrated or volume-depleted.
• Nausea or diarrhoea.
• Raised blood glucose, which may affect patients with or at risk of diabetes.
• Skin rash, itching, or increased sensitivity to sunlight (photosensitivity).

Serious Side Effects: Seek Urgent Medical Attention

Contact your prescriber or go to your nearest accident and emergency department promptly if you experience any of the following:

• Angioedema - sudden swelling of the face, lips, tongue, or throat. Although less common with ARBs than with ACE inhibitors, angioedema can occur with valsartan. If you experience throat swelling or difficulty breathing, seek emergency help immediately.
• Signs of significant kidney deterioration such as a marked reduction in urine output or significant swelling.
• Symptoms of very high potassium such as muscle weakness, an irregular heartbeat, or tingling.
• Severe dizziness, fainting, or signs of severe dehydration.
• Signs of a serious allergic reaction such as difficulty breathing or a severe skin reaction.

Report any suspected side effect to your prescriber or pharmacist or via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

Co-Diovan Tablets May Be Suitable If You:

• Are an adult with hypertension whose blood pressure is not adequately controlled on valsartan or hydrochlorothiazide monotherapy and who requires combination treatment.
• Have been established on separate valsartan and hydrochlorothiazide tablets at doses that correspond to one of the available Co-Diovan strengths, and your prescriber considers a combination tablet appropriate for ongoing treatment.
• Are already prescribed Co-Diovan and require a repeat prescription through an online prescribing service.

Co-Diovan Tablets Are Not Suitable If You:

• Are pregnant or planning to become pregnant - Co-Diovan must not be used during pregnancy.
• Have severe liver impairment, biliary cirrhosis, or cholestasis.
• Have severe kidney impairment (eGFR below 30 ml/min/1.73m2) or are anuric.
• Have refractory hypokalaemia (low potassium that cannot be corrected), hypercalcaemia, or hyponatraemia.
• Have gout.
• Are taking aliskiren alongside Co-Diovan if you have diabetes or kidney impairment (eGFR below 60 ml/min/1.73m2).
• Have a known allergy to valsartan, hydrochlorothiazide, sulfonamide-derived medicines, or any excipient in the SmPC.
• Are under 18 years of age (this service is for adults only).

Cautions

Particular caution is required in patients with mild to moderate kidney impairment. Kidney function, potassium, and sodium should be monitored at the start of treatment and periodically during treatment. Patients with bilateral renal artery stenosis or stenosis in a single functioning kidney are at increased risk of kidney impairment. Older patients and those taking high-dose diuretics are at greater risk of a significant first-dose fall in blood pressure. Patients with diabetes should be aware that hydrochlorothiazide can raise blood glucose levels and may affect glycaemic control.

Important Drug Interactions

Co-Diovan can interact with a number of commonly prescribed medicines. Tell your prescriber about all medicines you take, including over-the-counter products and herbal supplements. The following interactions are of particular clinical importance:

• Potassium-sparing diuretics, potassium supplements, or potassium-containing salt substitutes: combining these with the valsartan component can significantly raise potassium levels.
• ACE inhibitors: combining valsartan with an ACE inhibitor is not recommended in most patients, as it increases the risk of hypotension, hyperkalaemia, and kidney impairment.
• Aliskiren: the combination of valsartan with aliskiren is contraindicated in patients with diabetes or kidney impairment.
• Lithium: both valsartan and hydrochlorothiazide can raise lithium levels. Close monitoring is required if lithium is co-prescribed.
• NSAIDs such as ibuprofen: these can reduce the antihypertensive effect of Co-Diovan and increase the risk of kidney problems.
• Antidiabetic medicines: hydrochlorothiazide can raise blood glucose, potentially requiring adjustment of antidiabetic treatment.
• Digoxin: electrolyte changes caused by hydrochlorothiazide can increase the risk of digoxin toxicity. Monitoring is important in patients taking both medicines.

This is not a complete list of interactions. Your prescriber will carry out a full clinical assessment, including a review of your current medicines, before any prescription is considered.

Co-Diovan is a prescription-only medicine. The clinical consultation is the essential first step. A prescription will only be issued if a registered prescriber determines, based on their individual assessment of your circumstances, that Co-Diovan is clinically appropriate for you.

During your online consultation with Pharmacy Planet, a registered prescriber will review your clinical information. This includes your blood pressure readings; kidney function; electrolyte levels, including potassium and sodium; current medicines; and relevant medical history, including any previous ARB or diuretic use. The prescriber will also assess whether the fixed-dose combination corresponds to doses of both components that are clinically appropriate for your individual circumstances.

Not all consultations will result in a prescription being issued. The prescriber may recommend a different strength, the individual components at separately adjusted doses, or suggest that a face-to-face appointment with your GP is more appropriate. This process is designed to ensure your safety.

If you are already being managed for hypertension by your GP or a specialist, please keep them informed of all medicines you are taking, including any prescribed through online services.

• Store below 30°C.
• Store in the original packaging to protect from light and moisture.
• Keep out of the sight and reach of children.
• Do not use after the expiry date printed on the packaging.
• Do not dispose of medicines via household waste or wastewater. Return unused or out-of-date tablets to your pharmacist for safe disposal.

Full storage instructions are provided in the Patient Information Leaflet supplied with your medicine.

The table below compares ARB tablets and Rasilez (aliskiren), the only direct renin inhibitor licensed for hypertension in the UK. All act on the renin-angiotensin-aldosterone system (RAAS) and are taken once daily as tablets.

Important: This comparison is for general information only and does not replace medical advice. A prescriber will decide which treatment is suitable for you following an online consultation.

Pharmacy Planet is a GPhC-registered online pharmacy providing access to prescription medicines through a clinically led consultation process. Our registered prescribers and pharmacists are committed to patient safety, clinical accuracy, and responsible prescribing.

We follow GPhC standards, MHRA guidance, and ASA advertising regulations in all aspects of our service. Every prescription is reviewed and dispensed by qualified healthcare professionals. We provide clear, factual information to help patients understand their antihypertensive medication and make informed decisions about their health.

If you have questions about Co-Diovan, combination blood pressure treatment, or cardiovascular therapy, our pharmacy team is available to help. We are committed to transparent, patient-centred care.

References

1. Electronic Medicines Compendium (eMC). Co-Diovan Film-coated Tablets (Novartis Pharmaceuticals UK Ltd) — Summary of Product Characteristics. https://www.medicines.org.uk/emc. Accessed August 2026.
2. National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management. NICE guideline NG136. https://www.nice.org.uk/guidance/ng136. Accessed August 2026.
3. Joint Formulary Committee. British National Formulary (BNF). Valsartan with hydrochlorothiazide. BMJ Group and Pharmaceutical Press. https://bnf.nice.org.uk. Accessed August 2026.
4. NHS. Valsartan. https://www.nhs.uk/medicines/valsartan. Accessed August 2026.
5. Medicines and Healthcare products Regulatory Agency (MHRA). Yellow Card — report a side effect. https://yellowcard.mhra.gov.uk. Accessed August 2026.