Co-Amilofruse

Fluid retention and high blood pressure often occur together, particularly in people living with heart failure, kidney disease, or liver conditions. Co-amilofruse tablets are a prescription combination diuretic containing two complementary active ingredients: furosemide, a potent loop diuretic, and amiloride, a potassium-sparing diuretic. By combining these two medicines in a single tablet, co-amilofruse provides effective fluid removal while helping to reduce the potassium loss that furosemide alone can cause. Regular monitoring of kidney function and electrolytes is an essential part of safe treatment. A prescription can only be issued following a clinical consultation with a registered prescriber.

Co-amilofruse tablets are an oral prescription combination medicine containing two active ingredients: furosemide and amiloride hydrochloride. Furosemide is a loop diuretic and amiloride is a potassium-sparing diuretic. Together they are referred to by the combination name co-amilofruse. The product is available in two fixed-dose combinations: 2.5mg amiloride with 20mg furosemide per tablet and 5mg amiloride with 40mg furosemide per tablet.

Co-amilofruse is licensed in the United Kingdom for the treatment of oedema (fluid retention) and, where appropriate, the management of high blood pressure, in patients who require both a loop diuretic and a potassium-sparing diuretic. It is typically prescribed for patients who have been established on the individual components at equivalent doses and who would benefit from the convenience of a single combination tablet. It may be used in oedema associated with congestive heart failure, hepatic cirrhosis, and renal disease.

All clinical information on this page is drawn from the current UK Summary of Product Characteristics for co-amilofruse tablets.

Important: Co-amilofruse requires regular monitoring of kidney function, potassium, sodium, and other electrolytes during treatment. Both active ingredients affect fluid and electrolyte balance. Imbalances can develop quickly, particularly in older patients or those with kidney impairment. Your prescriber will determine an appropriate monitoring schedule. Online prescribing is only appropriate where adequate clinical history and monitoring are in place.

Co-amilofruse works through the combined and complementary actions of its two active ingredients.

Furosemide: Loop Diuretic Action

Furosemide acts on the thick ascending limb of the loop of Henle in the kidney, where it blocks the sodium-potassium-chloride co-transporter. This prevents the reabsorption of sodium, potassium, and chloride from the filtered urine back into the bloodstream. Water follows these electrolytes, resulting in a marked and rapid increase in urine output. This removes excess fluid from the body, reducing oedema and lowering blood pressure. A significant drawback of furosemide alone is that it promotes potassium excretion, which can lead to low blood potassium (hypokalaemia) over time.

Amiloride: Potassium-Sparing Action

Amiloride acts on the collecting duct of the kidney, where it blocks sodium channels that are stimulated by aldosterone. By blocking these channels, amiloride reduces the reabsorption of sodium without promoting potassium excretion. This counteracts the potassium-wasting effect of furosemide. The result is a combination that removes excess sodium and water effectively while helping to maintain potassium levels within a safer range. This reduces the need for separate potassium supplementation in many patients.

Combined Effect

Together, furosemide and amiloride provide a diuretic effect that is clinically meaningful for oedema and blood pressure management while reducing the risk of hypokalaemia compared to furosemide alone. However, the presence of amiloride means that co-amilofruse carries a risk of raised potassium (hyperkalaemia) in certain patients, particularly those with kidney impairment or those taking other medicines that raise potassium. Monitoring is essential for both components.

Always take co-amilofruse 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-amilofruse once daily in the morning or as directed by your prescriber. Taking it in the morning means the increase in urination occurs during the day rather than disturbing your sleep.
• Co-amilofruse can be taken with or without food.
• Swallow the tablet whole with a glass of water.
• 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-amilofruse without speaking to your prescriber first. Stopping a combination diuretic suddenly can cause fluid to accumulate rapidly, which may worsen breathlessness, swelling, and blood pressure.
• Attend all blood test and monitoring appointments arranged by your prescriber. Co-amilofruse affects both potassium and kidney function, and these require regular review throughout treatment.

Co-amilofruse produces a significant increase in urination for several hours after each dose. Plan your daily activities with this in mind, particularly when starting treatment or after a dose adjustment.

Co-amilofruse tablets are available in two fixed-dose combination strengths through this service. The doses of both active ingredients are expressed together as amiloride/furosemide. The appropriate strength will be determined by your prescriber based on the condition being treated, your kidney function, electrolyte levels, and response to treatment. Co-amilofruse is intended for patients who have already been established on the individual components at equivalent doses and where a fixed combination is clinically appropriate.

Co-amilofruse 2.5mg/20mg Tablets

Each tablet contains 2.5mg of amiloride hydrochloride and 20mg of furosemide. This is the lower strength combination, equivalent to half the dose of the higher strength tablet. It is used in patients requiring a lower level of diuresis, those who are more sensitive to the effects of diuretic therapy (such as older patients), or those in whom the 5mg/40mg strength would provide more diuresis than is clinically required. Your prescriber will advise whether this strength is appropriate for your circumstances.

Co-amilofruse 5mg/40mg Tablets

Each tablet contains 5mg of amiloride hydrochloride and 40mg of furosemide. This is the standard strength combination and corresponds to the most commonly prescribed doses of amiloride 5mg and furosemide 40mg as separate tablets. It is used in patients with oedema or hypertension requiring a moderate level of diuresis who have been established on equivalent doses of both components. All dosing decisions are made by your prescriber. Do not change your dose without medical advice.

Like all medicines, co-amilofruse can cause side effects. Because it contains two active ingredients, it carries the potential side effects of both furosemide and amiloride. 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)

• Increased frequency of urination, particularly in the first few hours after taking the tablet. This is an expected effect of diuretic therapy.
• Dizziness or lightheadedness, particularly when standing up quickly (postural hypotension).
• Low sodium levels (hyponatraemia), which may cause fatigue, confusion, headache, or nausea.
• Thirst and dry mouth due to fluid loss.
• Raised blood uric acid levels, which may trigger or worsen gout in susceptible patients.

Electrolyte Effects Requiring Monitoring

Co-amilofruse can affect both potassium and other electrolytes in opposing directions depending on the balance of the two active ingredients and individual patient factors.

• Low potassium (hypokalaemia): furosemide promotes potassium loss. Although amiloride helps to offset this, low potassium can still occur, particularly at higher doses or in patients with significant fluid loss. Symptoms include muscle cramps, weakness, and an irregular heartbeat.
• High potassium (hyperkalaemia): amiloride reduces potassium excretion and can raise potassium levels, particularly in patients with kidney impairment, diabetes, or those also taking ACE inhibitors, ARBs, or other potassium-raising medicines. Symptoms include muscle weakness, an irregular heartbeat, and tingling.

Regular blood tests allow your prescriber to identify and manage both types of electrolyte disturbance. Always attend monitoring appointments.

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:

• Severe muscle weakness, significant cramps, or an irregular heartbeat, which may indicate a serious electrolyte imbalance.
• Significant reduction in urine output, which may indicate worsening kidney function or excessive dehydration.
• Signs of severe dehydration such as extreme thirst, very dark urine, dizziness, and confusion.
• Signs of a serious allergic reaction, such as sudden swelling of the face, lips, tongue, or throat; difficulty breathing; or a severe skin reaction.
• Sudden severe joint pain, redness, and swelling, which may indicate a gout attack.

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

Co-amilofruse Tablets May Be Suitable If You:

• Are an adult with oedema associated with heart failure, liver disease, or kidney disease who has been established on equivalent doses of amiloride and furosemide as separate tablets and where a combination product is clinically appropriate.
• Require both a loop diuretic and a potassium-sparing diuretic and your prescriber considers a fixed-dose combination suitable for your management.
• Are already prescribed co-amilofruse and require a repeat prescription through an online prescribing service, with adequate recent monitoring results available.

Co-amilofruse Tablets Are Not Suitable If You:

• Have hyperkalaemia (raised blood potassium levels).
• Have severe kidney impairment or kidney failure, or are anuric (producing no urine).
• Have Addison's disease (adrenal insufficiency).
• Are taking other potassium-sparing diuretics, potassium supplements, or potassium-containing salt substitutes.
• Are in hepatic coma or pre-coma associated with severe liver disease.
• Are severely dehydrated or have a significant reduction in circulating blood volume.
• Are pregnant or breastfeeding.
• Have a known allergy to amiloride, furosemide, sulfonamide-derived medicines, or any excipient listed in the SmPC.
• Are under 18 years of age (this service is for adults only).

Cautions

Particular caution is required in older patients, who are at greater risk of dehydration, electrolyte disturbances, and postural hypotension. Patients with diabetes should be aware that loop diuretics can affect blood glucose levels. Patients with gout or a history of raised uric acid levels should be monitored, as furosemide raises uric acid. Patients with enlarged prostate or urinary outflow problems may develop urinary retention due to the rapid increase in urine production.

Important Drug Interactions

Co-amilofruse 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:

• ACE inhibitors and ARBs: combining these with co-amilofruse can significantly raise potassium levels (risk from amiloride) and cause a significant first-dose fall in blood pressure (risk from furosemide). Close monitoring is essential.
• Digoxin: electrolyte changes caused by co-amilofruse, particularly changes in potassium, increase the risk of digoxin toxicity. Electrolyte monitoring is essential in patients taking both medicines.
• Lithium: furosemide can increase lithium blood levels, raising the risk of lithium toxicity. Close monitoring is required.
• NSAIDs such as ibuprofen: these can reduce the diuretic effect of both components and increase the risk of kidney problems. Avoid regular use of NSAIDs while taking co-amilofruse.
• Aminoglycoside antibiotics: concurrent use with furosemide may increase the risk of hearing damage and kidney toxicity.
• Antidiabetic medicines: furosemide can raise blood glucose levels, which may affect antidiabetic treatment requirements.

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-amilofruse is a prescription-only medicine that requires ongoing clinical monitoring. 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-amilofruse is clinically appropriate for you.

During your online consultation with Pharmacy Planet, a registered prescriber will review your clinical information. This includes your diagnosis; kidney function results; electrolyte levels, including potassium and sodium; other medicines you are taking; and any relevant medical history. Because co-amilofruse contains two diuretics and requires regular monitoring, the prescriber will also assess whether adequate monitoring is in place before considering whether to issue a prescription. Co-amilofruse is a fixed combination and is generally not appropriate for patients who require doses of amiloride and furosemide that do not correspond to the available fixed ratios.

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

If you are already being managed for heart failure, oedema, or a renal or hepatic condition by your GP or a hospital team, please keep them informed of all medicines you are taking, including any prescribed through online services.

• Store below 25°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 diuretic tablets available at Pharmacy Planet. Diuretics lower blood pressure and reduce fluid retention by increasing urine production. Different classes of diuretic work at different sites in the kidney.

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 diuretic medication and make informed decisions about their health.

If you have questions about co-amilofruse, diuretic therapy, or fluid and blood pressure management, our pharmacy team is available to help. We are committed to transparent, patient-centred care.

References

1. Electronic Medicines Compendium (eMC). Co-amilofruse 2.5mg/20mg and 5mg/40mg Tablets — Summary of Product Characteristics. https://www.medicines.org.uk/emc. Accessed August 2026.
2. National Institute for Health and Care Excellence (NICE). Chronic heart failure in adults: diagnosis and management. NICE guideline NG106. https://www.nice.org.uk/guidance/ng106. Accessed August 2026.
3. Joint Formulary Committee. British National Formulary (BNF). Co-amilofruse. BMJ Group and Pharmaceutical Press. https://bnf.nice.org.uk. Accessed August 2026.
4. NHS. Furosemide. https://www.nhs.uk/medicines/furosemide. 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.