ACE inhibitors and angiotensin II receptor blockers

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are medicines that widen your blood vessels and so, lower your blood pressure. They can treat high blood pressure, and heart and kidney problems.

Uses of ACE inhibitors and ARBs

Your doctor may recommend you take an ACE inhibitor or an ARB to lower your blood pressure if you have:

high blood pressure (hypertension)
heart failure, or have had a heart attack
diabetes , and there are signs of problems with your kidneys
kidney disease

These medicines aren’t suitable for everyone, so let your doctor know if you have any other health conditions or take other medicines. If you’re trying for a baby or are breastfeeding, let your doctor know too as they’ll need to take this into consideration.

It’s your choice whether to take a medicine or not. Discuss your options with your doctor and ask them about the pros and cons of any medicines they suggest.

How ACE inhibitors and ARBs work

ACE inhibitors and ARBs lower your blood pressure and make it easier for your heart to pump blood round your body.

They do this by acting on one of the systems your body has to control your blood pressure. If your blood pressure drops too low, your body will produce a chemical called angiotensin I. An enzyme called angiotensin-converting enzyme (ACE) converts (changes) this into angiotensin II. Angiotensin II narrows your blood vessels and triggers the release of a hormone that makes your body hold on to water. The extra volume of fluid in your blood and the narrowing of your blood vessels make your blood pressure rise again.

Here’s how ACE inhibitors and ARBs work on this system.

ACE inhibitors block the action of angiotensin-converting enzyme so that angiotensin I isn't converted to angiotensin II.
ARBs block the action of angiotensin II. You may also see these medicines called angiotensin II receptor ‘antagonists’.

If you have kidney disease, as well as lowering your blood pressure, ACE inhibitors and ARBs can also help your kidneys work better for longer.

Types of ACE inhibitors and ARBs

There are lots of different ACE inhibitors. Examples include enalapril (eg Innovace) and ramipril (eg Tritace). There are also different types of ARBs, which include candesartan (eg Amias) and losartan (eg Cozaar-Comp). They work as well as each other, and ARBs usually have fewer side-effects.

Your doctor will normally decide which is best for you after they consider a number of things. These include:

what health condition you have
if you have any other health problems

Your doctor will usually prescribe you an ACE inhibitor first. If you get the side-effect of a troublesome cough, your doctor may offer you an ARB instead. Ask your doctor for more information about what the best medicine is for you..

Taking ACE inhibitors and ARBs

You’ll usually need to take ACE inhibitors or ARBs on a long-term basis and have regular check-ups with your doctor. Your doctor will ask you to have a blood test before you start these medicines. They’ll test you again a week or two after you first take the medicine, or if they increase your dose.

After this, your doctor will test you every year. These tests are to check:

your kidneys are healthy
your blood pressure is responding well to your medicine

You take ACE inhibitors or ARBs as tablets usually once a day. When you have your first dose, your doctor may advise you that it’s best to take it at night. If everything is well and you don’t get bad side-effects, you can take the tablets every morning. Your doctor may start you on a low dose, then increase this gradually over a few weeks or months to reach the most effective dose.

The patient information leaflet that comes with your medicine will tell you more about how to take your tablets. Read it carefully. With some tablets it’s important not to crush or chew them, just swallow them whole with a drink of water. If you have any questions or concerns about taking your medicine, ask your pharmacist.

Interactions of ACE inhibitors and ARBs

ACE inhibitors and ARBs can interact with other medicines and cause unwanted effects. For instance, if you take some medicines together with ACE inhibitors or ARBs, it can give you very low blood pressure (hypotension) or very high potassium levels in your blood. The same effect can happen if you take both ACE inhibitors and ARBs together, so your doctor won’t usually prescribe you both.

Check with your doctor before you take any other medicines or supplements at the same time as ACE inhibitors or ARBs.

Side-effects of ACE inhibitors and ARBs

Like all medicines, ACE inhibitors and ARBs can cause side-effects for some people. Possible side-effects of ACE inhibitors and ARBs include:

low blood pressure, which may make you feel dizzy
a persistent dry cough if you take ACE inhibitors (you don’t usually get this side-effect with ARBs)
headaches
tummy (abdominal) discomfort, diarrhoea, constipation, feeling sick or vomiting

Your kidneys may not work as well as they did before you took ACE inhibitors and ARBs.

We haven’t included all the possible side-effects here. Your patient information leaflet will have more information about side-effects and how common they are. ARBs usually have milder side-effects than ACE inhibitors.

If you get these, or other side-effects with ACE inhibitors, contact your doctor. They may reduce the dose of your medicine or change to another medicine.

Frequently asked questions

Can I drink alcohol with ACE inhibitors or ARBs?

What is the difference between ACE inhibitors and angiotensin receptor blockers?

Can ARBs and ACE inhibitors be used together?

Which is better ARBs or ACE inhibitors?

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