Angiotensin-converting enzyme (ACE) inhibitors are medicines that are used to treat high blood pressure. They also reduce protein leaking from the kidneys.
How do ACE inhibitors work?
ACE inhibitors reduce the amount of angiotensin II that your body produces,
Angiotensin II makes your blood vessels contract, so they become narrower and your blood has a smaller space to flow through, which increases the pressure. Angiotensin II also keeps extra water in your kidneys rather than passing into your urine. This puts pressure on the walls of your blood vessels.
By reducing angiotensin II, ACE inhibitors help to relax and widen the blood vessels to allow more blood to flow to your kidneys and heart. ACE inhibitors also allow more water to be released into your urine which lowers your blood pressure.
Why might I be prescribed ACE inhibitors?
One in two people with chronic kidney disease (CKD) have high blood pressure. High blood pressure can cause CKD and CKD can cause high blood pressure. Controlling your blood pressure helps to reduce the strain on your kidneys and can prevent your kidney disease from getting worse.
If you have diabetes and CKD or your kidneys are losing protein you may be prescribed ACE inhibitors even if your blood pressure is under control, as these medicines can protect your kidney function and heart health by reducing protein loss
What kinds of ACE inhibitors are available?
There are different types of ACE inhibitors, and your doctor will discuss which ones might be suitable for you.
You will normally be prescribed a low dose first, which will then be increased if needed.
ACE inhibitor medicine names end in ‘pril’. For example:
- lisinopril
- perindopril
- ramipril
You can find out more about these specific medicines on the NHS Medicines A to Z website.
How do I take ACE inhibitors?
ACE inhibitors are taken as tablets. They can be taken with or without food. Most are taken once a day.
Try to take the tablets at the same time each day, ideally before the first meal of the day.
If you miss your normal time slot and remember later in the day, take the tablet then. If you do not remember until the next day, just take that day’s dose – do not take two doses together.
How long will I need to take ACE inhibitors for?
ACE inhibitors are a long-term treatment and you will likely be on them for many years. The dose and type of medicine may change over time.
Always consult your GP, kidney doctor or pharmacist before changing or starting any medications.
My doctor mentioned ‘Sick Day Rules’. What does that mean?
Taking certain medicines when you are unwell can lead to more severe illness. ‘Sick Day Rules’ is advice about how to take your medicine if you are unwell and become dehydrated.
Dehydration occurs if you are unable to drink fluid or have diarrhoea or vomiting. Your doctor or nurse may suggest that you stop your ACE inhibitor until you have been eating and drinking normally again for at least 48 hours.
Are there any side effects of taking ACE inhibitors?
Like all medicines, ACE inhibitors can cause side effects, but these are usually temporary and mild.
Common side effects include:
- a dry cough
- tiredness
- headaches
- dizziness
Talk to your doctor if any side effects do not away after a few weeks. They may suggest a different dose or type of ACE inhibitor.
If the side effects of ACE inhibitors become too much to manage, your doctor may suggest that change to an angiotensin-II receptor blocker (ARB) which is a similar type of blood pressure medication.
Both ACE inhibitors and ARB medications can increase your risk of developing acute kidney injury (AKI) (a sudden drop in kidney function). You can reduce this risk by avoiding non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, and by remaining well hydrated by drinking plenty of water.
Taking an ACE inhibitor as well an ARB is not generally recommended as it can cause high potassium (hyperkalaemia).
How will I be monitored if I take ACE inhibitors?
Your healthcare team will monitor your kidney function and potassium levels for 2 to 4 weeks after starting or changing the dose of ACE inhibitors. You will have regular blood pressure checks to make sure the ACE inhibitors are working.
You will have extra blood tests if you are taking a diuretic (water tablet) as well as an ACE inhibitor as both medicines can reduce the blood flow through your kidneys and it is important that this doesn’t drop too low.
Tell your healthcare team if you are pregnant or trying to get pregnant as ACE inhibitors should not be taken during pregnancy.
Do I need to change my diet if I am taking ACE inhibitors?
Following a low-salt diet can help the ACE inhibitors to work better by further reducing pressure on your heart.
You should avoid taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. Indigestion medicines like Gaviscon are high in sodium so should also be avoided unless advised by your health professional.
Can I take ACE inhibitors if I am having dialysis?
Sometimes blood pressure medicines like ACE inhibitors can cause your blood pressure to fall too low during haemodialysis.
If this happens, your doctor may change the type of medication you are prescribed or suggest that you take it at a different time of day - for example, taking them at night if you have dialysis in the morning.
Looking after your medicines
You should store your medicines in their original packet in a cool, dry place, out of the sight and reach of children.
Do not get rid of any expired or unwanted tablets by flushing them down the toilet or throwing them away. Take them to your local pharmacy who will dispose of them for you.
Where can I find out more information?
Focus on high blood pressure and kidney disease | Kidney Care UK
Publication date: 11/2026
Review date: 11/2029