Cardiovascular
ACE inhibitors
Angiotensin-converting enzyme inhibitors — First-line drugs for hypertension, heart failure and kidney protection — names ending in "-pril".
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
ACE inhibitors are a cornerstone class in cardiovascular and renal medicine. They are used to lower blood pressure, treat and prevent the progression of heart failure, and protect the kidneys in people with diabetes or chronic kidney disease. You can usually recognise them by the "-pril" ending.
How it works
They block angiotensin-converting enzyme, reducing production of angiotensin II — a hormone that narrows blood vessels and drives sodium and water retention. The result is vasodilation, lower blood pressure, reduced cardiac workload and a fall in pressure within the kidney's filtering units, which is what gives the long-term kidney-protective effect. The same pathway explains the two characteristic effects to watch for: a dry cough (from bradykinin build-up) and a rise in potassium and creatinine.
In practice
In practice, start low — especially in older or volume-depleted patients — and check renal function and potassium a week or two after starting or increasing the dose. A creatinine rise of up to roughly a quarter can be expected and tolerated; a larger jump prompts review for renal-artery disease or over-diuresis. If a troublesome dry cough develops, switching to an angiotensin-receptor blocker keeps the same benefits without the bradykinin effect.
Examples
Practical use
How to take it & use it well
- Take it at the same time each day to keep a steady level in your body. Many people take their first dose at bedtime because it can cause dizziness when you start.
- You can take it with or without food. Try to build a routine, such as taking it with breakfast or before bed, so you do not forget.
- Stand up slowly from sitting or lying down for the first few days, as these drugs can lower your blood pressure and make you feel light-headed.
- If you miss a dose, take it as soon as you remember on the same day. If it is nearly time for the next one, skip the missed dose and carry on as normal. Do not double up.
- If you develop a dry, tickly cough that will not settle, tell your GP or pharmacist rather than stopping on your own. There are alternatives that do not cause this.
- Do not stop taking it suddenly without advice, even if you feel well, as your blood pressure may rise again.
Common uses
- Hypertension
- Heart failure with reduced ejection fraction
- After myocardial infarction
- Diabetic and chronic kidney disease (proteinuria)
Monitoring
- Renal function and potassium before starting and after each dose increase
- Blood pressure
- A modest rise in creatinine can be acceptable; a large rise needs review
Weighing it up
Advantages & disadvantages
Advantages
- They lower blood pressure and ease the workload on the heart, and have strong evidence for protecting people with heart failure.
- They help protect the kidneys, especially in people with diabetes or early kidney problems, by reducing protein leaking into the urine.
- They are usually taken once a day, which makes them easy to fit into a daily routine.
- They are well studied, widely used on the NHS, and inexpensive.
- They do not usually cause weight gain or affect blood sugar levels.
Disadvantages
- A persistent dry cough is a common side effect that leads some people to switch to a different class.
- They can raise potassium levels and affect kidney function, so blood tests are needed when starting and after dose changes.
- They can cause dizziness or low blood pressure, particularly with the first dose or when dehydrated.
- Rarely they can cause swelling of the face, lips, tongue or throat (angioedema), which is a medical emergency.
- They are not suitable in pregnancy and must be stopped if you are planning to conceive or become pregnant.
Key safety principles
What to watch for
- Avoid in pregnancy and in bilateral renal artery stenosis.
- Risk of hyperkalaemia — extra caution with potassium-sparing diuretics, potassium supplements and renal impairment.
- Can cause a sharp fall in blood pressure with the first dose, especially if the patient is volume-depleted or on a diuretic.
- Angioedema is rare but serious and can occur even after long-term use.
Key interactions
What to avoid or check alongside
- Taking them with anti-inflammatory painkillers (NSAIDs such as ibuprofen) can reduce their effect and increase the risk of kidney problems.
- Combining them with potassium supplements or potassium-sparing water tablets can push potassium too high, which affects the heart rhythm.
- Using them alongside other blood-pressure-lowering medicines or water tablets can cause your blood pressure to drop too low.
- Salt substitutes that contain potassium can add to the potassium-raising effect and are best avoided.
- Lithium levels can rise when taken with these drugs, so extra monitoring is needed.
- Drinking a lot of alcohol can add to the blood-pressure-lowering effect and increase dizziness.
Patient & carer advice
- A persistent dry cough is common — report it so an alternative (e.g. an ARB) can be considered
- Report swelling of the lips, tongue or face urgently
- Avoid over-the-counter NSAIDs and potassium-based salt substitutes unless advised
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
ACE inhibitors: frequently asked questions
How long until it starts working?
Your blood pressure usually starts to fall within hours, but the full benefit on blood pressure and on the heart or kidneys builds up over a few weeks of regular use.
Can I drink alcohol with it?
An occasional drink is usually fine, but alcohol can lower your blood pressure further and make you feel dizzy, so go carefully, especially when you first start.
Is it safe in pregnancy?
No. These medicines can harm a developing baby and should be stopped before or as soon as pregnancy is confirmed. Speak to your doctor about a safer alternative if you are planning to conceive.
Why have I developed a dry cough?
A dry, tickly cough is a known side effect of this class. It is not dangerous but can be annoying. Tell your GP, as switching to a similar medicine called an ARB usually resolves it.
Can I stop taking it suddenly?
Do not stop without advice. If you feel unwell or think it is causing side effects, speak to your GP or pharmacist so any change is managed safely.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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