Enalapril NHS: your complete patient guide

Enalapril is a medicine belonging to the class of angiotensin-converting enzyme (ACE) inhibitors.

It has been available in the UK for over 30 years and is one of the most commonly prescribed blood pressure medicines on the NHS.

Licensed indications:

• Hypertension (high blood pressure): enalapril lowers blood pressure by preventing the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor
• Heart failure: enalapril reduces the workload on the heart and has been shown to improve survival in patients with heart failure with reduced ejection fraction
• Prevention of symptomatic heart failure: in patients with asymptomatic left ventricular dysfunction

Other common uses:

• Diabetic nephropathy: ACE inhibitors protect the kidneys in patients with diabetes by reducing protein loss in the urine (proteinuria) and slowing the progression of kidney disease
• Chronic kidney disease with proteinuria: regardless of cause

How enalapril works:

Enalapril is a prodrug that is converted in the liver to its active form, enalaprilat. This blocks ACE, leading to:

• Reduced angiotensin II production (less vasoconstriction)
• Reduced aldosterone secretion (less salt and water retention)
• Increased bradykinin levels (additional vasodilation)

NICE recommends ACE inhibitors as first-line treatment for hypertension in patients under 55 (or of any age with type 2 diabetes).

Enalapril is available as tablets in 2.5 mg, 5 mg, 10 mg and 20 mg strengths. It is usually taken once or twice daily.

Dosing for hypertension:

• Starting dose: 5 mg once daily
• Maintenance dose: 10 to 20 mg once daily
• Maximum dose: 40 mg daily (may be given as a single dose or in two divided doses)
• If already on a diuretic: start with 2.5 mg and monitor blood pressure closely

Dosing for heart failure:

• Starting dose: 2.5 mg once daily
• Titration: increase gradually over 2 to 4 weeks based on response and tolerability
• Target dose: 10 to 20 mg twice daily
• Close monitoring of blood pressure, renal function and potassium during titration

Practical advice:

• Enalapril can be taken with or without food
• Swallow the tablets whole with water
• Try to take it at the same time each day for consistency
• If you miss a dose, take it as soon as you remember unless it is nearly time for the next dose
• Consider taking the first dose at bedtime to reduce the risk of first-dose hypotension

Dose adjustments:

• Renal impairment: dose reduction is needed if eGFR is below 30 ml/min
• Elderly patients: start with lower doses and titrate cautiously
• Children: enalapril is licensed for hypertension in children from 6 years of age (specialist prescribing)

Regular monitoring is essential when taking enalapril. Your GP surgery will typically arrange the following checks.

Before starting enalapril:

• Blood pressure measurement
• Blood test for kidney function (eGFR, creatinine) and electrolytes (sodium, potassium)
• Assessment of cardiovascular risk factors

After starting or changing the dose:

• Renal function and potassium should be checked within 1 to 2 weeks
• Blood pressure should be reviewed to assess response
• If stable, further blood tests at 3 months, then at least annually

Ongoing monitoring:

• Annual blood test for kidney function and electrolytes
• Regular blood pressure checks (at least annually; more often if not at target)
• Review of symptoms and side effects

What the blood tests look for:

• Rising creatinine or falling eGFR: may indicate that enalapril is affecting kidney function. A rise of up to 30% from baseline is generally accepted; larger rises may require dose reduction or discontinuation
• High potassium (hyperkalaemia): enalapril can cause potassium retention. Levels above 5.5 mmol/L require attention
• Low sodium (hyponatraemia): less common but may occur

If you are asked to attend for a blood test, please do not miss the appointment. These checks are an important safety measure.

The NHS lists the following side effects for enalapril. Many are mild and manageable.

Common side effects:

• Dry, tickly cough (the most characteristic ACE inhibitor side effect)
• Dizziness, especially when standing up
• Headache
• Diarrhoea
• Feeling tired or weak
• Blurred vision
• Mild rash

Serious side effects (seek medical advice promptly):

• Swelling of the face, lips, tongue or throat (angioedema)
• Yellowing of the skin or whites of the eyes (jaundice)
• Chest pain or irregular heartbeat
• Pale skin, feeling tired, faintness, or sore throat (possible blood disorder)

For a comprehensive 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 through the Yellow Card Scheme at yellowcard.mhra.gov.uk.

Enalapril interacts with several commonly prescribed medicines. Always tell your prescriber and pharmacist about all medicines you are taking.

Important interactions:

• NSAIDs (e.g. ibuprofen, naproxen): reduce the blood pressure-lowering effect of enalapril and increase the risk of kidney damage and hyperkalaemia. Occasional short-term use of ibuprofen is usually acceptable, but regular use should be avoided
• Potassium-sparing diuretics (e.g. spironolactone, amiloride): increase the risk of high potassium. Close monitoring is required
• Potassium supplements: generally should be avoided unless specifically prescribed with monitoring
• Lithium: enalapril can increase lithium levels, raising the risk of toxicity
• Aliskiren: dual RAAS blockade is not recommended, especially in patients with diabetes or renal impairment
• Trimethoprim and co-trimoxazole: increase the risk of hyperkalaemia

Who should not take enalapril:

• Anyone with a history of angioedema (with or without previous ACE inhibitor use)
• Pregnant women or those planning pregnancy (ACE inhibitors are teratogenic)
• Patients with bilateral renal artery stenosis
• Patients with hereditary or idiopathic angioedema

Cautions:

• Aortic or mitral stenosis
• Hypertrophic cardiomyopathy
• Collagen vascular disease (increased risk of neutropenia)
• Patients undergoing desensitisation therapy or LDL apheresis (risk of anaphylactoid reactions)

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

The prescribing pathway:

• Your GP or hospital specialist will assess whether enalapril is appropriate for you based on NICE guidelines
• For high blood pressure, NICE recommends ACE inhibitors as first-line treatment for patients under 55 or those with type 2 diabetes
• For heart failure, ACE inhibitors are a cornerstone of treatment recommended by NICE

Cost and availability:

• Enalapril is available generically and is very inexpensive for the NHS
• Standard NHS prescription charges apply (unless you are exempt)
• It is not a controlled substance and can be issued on repeat prescriptions

What to expect at your appointment:

• Blood pressure measurement
• Discussion of your cardiovascular risk factors
• Blood tests for kidney function and electrolytes
• Explanation of the medicine, its benefits and potential side effects
• A follow-up appointment within 2 to 4 weeks to check blood pressure and blood results

Alternatives if enalapril is not suitable:

If you develop a troublesome cough or other side effects, your GP may switch you to:

• An ARB (e.g. losartan, candesartan): similar benefits without the cough
• A calcium channel blocker (e.g. amlodipine): if ACE inhibitors and ARBs are not tolerated

NICE provides a clear stepped approach to blood pressure management, and your GP will work through the options with you.