Enalapril NHS: your complete patient guide

Enalapril is an angiotensin-converting enzyme (ACE) inhibitor. It has been used in the UK for over 30 years.

It is one of the most common blood pressure medicines prescribed on the NHS.

Approved uses:

• High blood pressure (hypertension): Enalapril lowers blood pressure. It stops angiotensin I from changing into angiotensin II. Angiotensin II narrows blood vessels.
• Heart failure: Enalapril reduces the heart's workload. It improves survival for patients with heart failure and reduced ejection fraction.
• Preventing symptomatic heart failure: This is for patients with asymptomatic left ventricular dysfunction.

Other common uses:

• Diabetic kidney disease (nephropathy): ACE inhibitors protect the kidneys in diabetes. They reduce protein loss in urine (proteinuria). They also slow kidney disease progression.
• Chronic kidney disease with proteinuria: This applies regardless of the cause.

How enalapril works:

Enalapril is a prodrug. The liver changes it into its active form, enalaprilat. This blocks ACE, which leads to:

• Less angiotensin II production, meaning less blood vessel narrowing.
• Less aldosterone secretion, meaning less salt and water retention.
• More bradykinin, which further widens blood vessels.

NICE suggests ACE inhibitors as first-line treatment for high blood pressure. This applies to patients under 55. It also applies to any age group with type 2 diabetes.

Enalapril comes as tablets in 2.5 mg, 5 mg, 10 mg, and 20 mg strengths. You usually take it once or twice a day.

Dosing for high blood pressure:

• Starting dose: Take 5 mg once daily.
• Maintenance dose: Take 10 to 20 mg once daily.
• Maximum dose: Take 40 mg daily. You can take this as one dose or two divided doses.
• If you already take a diuretic: Start with 2.5 mg. Your blood pressure will be closely monitored.

Dosing for heart failure:

• Starting dose: Take 2.5 mg once daily.
• Increasing the dose: Increase it slowly over 2 to 4 weeks. This depends on how you respond and tolerate it.
• Target dose: Aim for 10 to 20 mg twice daily.
• Your blood pressure, kidney function, and potassium will be closely checked while increasing the dose.

Practical advice:

• You can take enalapril with or without food.
• Swallow the tablets whole with water.
• Try to take it at the same time each day. This helps with consistency.
• If you miss a dose, take it when you remember. Do this unless it is almost time for your next dose.
• Consider taking the first dose at bedtime. This lowers the risk of low blood pressure after the first dose.

Dose adjustments:

• Kidney problems: You need a lower dose if your eGFR is below 30 ml/min.
• Elderly patients: Start with lower doses. Increase them carefully.
• Children: Enalapril is approved for high blood pressure in children from 6 years old. A specialist must prescribe it.

Regular monitoring is vital when you take enalapril. Your GP surgery will usually arrange these checks.

Before starting enalapril:

• Your blood pressure will be measured.
• You will have a blood test for kidney function (eGFR, creatinine). Electrolytes (sodium, potassium) will also be checked.
• Your cardiovascular risk factors will be assessed.

After starting or changing the dose:

• Kidney function and potassium should be checked within 1 to 2 weeks.
• Your blood pressure will be reviewed to see how you are responding.
• If stable, further blood tests are needed at 3 months. Then, they are needed at least once a year.

Ongoing monitoring:

• An annual blood test for kidney function and electrolytes is needed.
• Regular blood pressure checks are needed (at least yearly). More often if your blood pressure is not at target.
• Your symptoms and side effects will be reviewed.

What the blood tests look for:

• Rising creatinine or falling eGFR: This may show enalapril is affecting kidney function. A rise of up to 30% from your baseline is generally acceptable. Larger rises may mean you need a lower dose or to stop the medicine.
• High potassium (hyperkalaemia): Enalapril can cause potassium to build up. Levels above 5.5 mmol/L need attention.
• Low sodium (hyponatraemia): This is less common, but it can happen.

If you are asked to have a blood test, please attend. These checks are an important safety measure.

The NHS lists these side effects for enalapril. Many are mild and can be managed.

Common side effects:

• A dry, tickly cough. This is the most typical ACE inhibitor side effect.
• Dizziness, especially when you stand up.
• Headache.
• Diarrhoea.
• Feeling tired or weak.
• Blurred vision.
• A mild rash.

Serious side effects (seek medical advice quickly):

• Swelling of your face, lips, tongue, or throat (angioedema).
• Yellowing of your skin or the whites of your eyes (jaundice).
• Chest pain or an irregular heartbeat.
• Pale skin, feeling tired, faintness, or a sore throat. These could be signs of a blood disorder.

For a full discussion of enalapril side effects, including the ACE inhibitor cough and how to manage it, see our detailed enalapril side effects page.

You can report suspected side effects to the MHRA. Use the Yellow Card Scheme at yellowcard.mhra.gov.uk.

Enalapril interacts with several common medicines. Always tell your prescriber and pharmacist about all medicines you take.

Important interactions:

• NSAIDs (e.g., ibuprofen, naproxen): These reduce enalapril's blood pressure-lowering effect. They also increase the risk of kidney damage and high potassium. Short-term, occasional ibuprofen is usually fine. But avoid regular use.
• Potassium-sparing diuretics (e.g., spironolactone, amiloride): These increase the risk of high potassium. Close monitoring is needed.
• Potassium supplements: Generally avoid these. Only take them if specifically prescribed and monitored.
• Lithium: Enalapril can raise lithium levels. This increases the risk of toxicity.
• Aliskiren: Do not use dual RAAS blockade. This is especially true for patients with diabetes or kidney problems.
• Trimethoprim and co-trimoxazole: These increase the risk of high potassium.

Who should not take enalapril:

• Anyone with a history of angioedema. This includes cases with or without previous ACE inhibitor use.
• Pregnant women or those planning pregnancy. ACE inhibitors can harm an unborn baby.
• Patients with narrowing of both kidney arteries (bilateral renal artery stenosis).
• Patients with hereditary or idiopathic angioedema.

Cautions:

• Aortic or mitral valve narrowing.
• Hypertrophic cardiomyopathy.
• Collagen vascular disease. This increases the risk of low white blood cell count (neutropenia).
• Patients having desensitisation therapy or LDL apheresis. There is a risk of severe allergic reactions.

Enalapril is widely available on NHS prescription. It is one of the most cost-effective blood pressure medicines.

The prescribing process:

• Your GP or hospital specialist will decide if enalapril is right for you. They will follow NICE guidelines.
• For high blood pressure, NICE recommends ACE inhibitors as first-line treatment. This is for patients under 55 or those with type 2 diabetes.
• For heart failure, ACE inhibitors are a key treatment. NICE recommends them.

Cost and availability:

• Enalapril is available as a generic medicine. It is very cheap for the NHS.
• Standard NHS prescription charges apply. You will pay unless you are exempt.
• It is not a controlled substance. You can get it on repeat prescriptions.

What to expect at your appointment:

• Your blood pressure will be measured.
• You will discuss your cardiovascular risk factors.
• You will have blood tests for kidney function and electrolytes.
• The medicine will be explained to you. This includes its benefits and possible side effects.
• You will have a follow-up appointment within 2 to 4 weeks. This is to check blood pressure and blood test results.

Alternatives if enalapril is not suitable:

If you get a bothersome cough or other side effects, your GP may switch you to:

• An ARB (e.g., losartan, candesartan): These offer similar benefits without the cough.
• A calcium channel blocker (e.g., amlodipine): This is an option if you cannot tolerate ACE inhibitors and ARBs.

NICE provides a clear step-by-step approach to managing blood pressure. Your GP will discuss the options with you.