Angiotensin-II receptor blockers (ARBs) are medicines that are used to treat high blood pressure They also reduce protein leaking from the kidneys.
How do ARBs work?
ARBs 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.
ARBs block the receptors that angiotensin II normally uses to narrow your blood vessels. This helps to relax and widen the blood vessels to allow more blood to flow to your heart. ARBs also allow more water to be released into your urine. This lowers your blood pressure.
Why might I be prescribed ARBs?
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
You may be prescribed ARBs if you have had side effects from angiotensin-converting enzyme (ACE) inhibitors, which are another type of blood pressure medication.
What kinds of ARBs are available?
There are lots of different types of ARBs 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.
ARB medicine names end in ‘sartan’. For example:
- losartan
- candesartan
- irbesartan
- valsartan
You can find out more about these specific medicines on the NHS Medicines A to Z website.
How do I take ARBs?
ARBs are taken as tablets, once a day. They can be taken with or without food.
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 ARBs for?
ARBs 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 ARBs until you have been eating and drinking normally again for at least 48 hours.
Are there any side effects of taking ARBs?
Like all medicines, ARBs can cause side effects but these are usually temporary and mild.
Common side effects include:
- 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 ARB.
ARBs 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 ARB as well an ACE inhibitor is not generally recommended as it can cause high potassium (hyperkalaemia).
How will I be monitored if I take ARBs?
Your healthcare team will monitor your kidney function and potassium levels for 2 to 4 weeks after starting or changing the dose of ARBs. You will have regular blood pressure checks to make sure the ACE inhibitors are working.
You are unlikely to need any extra blood tests unless you feel unwell or your healthcare team think there could be a medication side effect.
Tell your healthcare team if you are breastfeeding, pregnant or trying to get pregnant as ARBs may affect your baby.
Do I need to change my diet if I am taking ARBs?
Some foods or ingredients can stop ARBs from working properly or increase the chance of side effects. These include:
- grapefruit and grapefruit juice
- potassium supplements
- salt substitutes that contain added potassium
You should also avoid taking nonsteroidal anti-inflammatory drugs (NSAID) such as ibuprofen.
Can I take ARBs if I am having dialysis?
Sometimes blood pressure medicines like ARBs 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