Angiotensin receptor blockers (ARBs) are a type of medicine often used to treat high blood pressure.
They work mainly by allowing the blood vessels to relax and widen so the blood has more space to flow through. Most have names that end in ‘artan’, for example, candesartan, irbesartan, losartan, valsartan and olmesartan.
How do ARBs work?
ARBs block the effects of a hormone called angiotensin II in your body.
Angiotensin II raises your blood pressure in two ways. It makes the muscles in your blood vessel walls contract, making the blood vessels narrower so your blood has less space to flow through. Angiotensin II also acts on the kidneys, causing them to keep water in your blood stream rather than releasing it in your urine. With more fluid in the blood, there is more pressure on the blood vessel walls.
ACE inhibitors allow your blood vessels to relax and widen, and for fluid to be removed from your blood and released in your urine, lowering you blood pressure.
Who can take ARBs?
If you have high blood pressure your doctor or nurse might suggest you take medicines to lower it. It can take some trial and error to find the right one or the right combination, and ARBs are often one of the first ones you will try, either on their own or alongside another one.
They’re often suitable if you’re under 55 and not of African or Caribbean descent, but can still be an option if that doesn’t apply to you. ARBs are usually used if another type of medicine called ACE inhibitors are causing side effects. These medicines work in similar ways, so you probably won’t take both at the same time.
When are ARBs not suitable?
ARBs are not suitable if you’re pregnant, breastfeeding or planning to get pregnant.
ARBs can occasionally interfere with other health problems or medicines you’re taking. Your doctor will consider your overall health and any treatments you’re having before giving you any new medicines.
Do ARBs have side-effects?
All medicines can have side effects, including blood pressure medicines. It’s likely you won’t have any side effects at all with ARBs, or you might have some that are minor and don’t cause you too many problems.
If you have side effects which don’t improve and are affecting your day-to-day life, speak to your GP because you should be able to try a lower dose or a different medicine.
Possible side effects of ARBs include:
- a sudden drop in blood pressure when you go from lying or sitting down to standing up (postural hypotension)
- cold or flu-like symptoms
- swelling around the mouth, face or throat (angio-oedema). This is an allergic reaction and it’s very rare. If it’s hard to breathe or swallow, stop taking the medication and contact your doctor
The leaflet that comes with your medicine will have a full list of possible side effects.
You take ARBs as a tablet, usually once a day. They can also be part of a combined tablet – where more than one medicine is combined in one tablet – for example with calcium-channel blockers or diuretics.
When you first start
They can start working very quickly. You will probably start with a low dose and will have blood tests and blood pressure checks to see how your body is responding.
Angiotensin receptor blockers seem to work better if you also eat less salt.
In the long term
Check with your doctor or pharmacist before taking any other medicines at the same time as ACE inhibitors, as they can interact, including medicines you buy over the counter such as painkillers and anti-inflammatories.
If you start taking high blood pressure medicines, it’s likely you will need to keep taking them for the long term. If your blood pressure stays under control for several years, you might be able to take a lower dose or stop taking them altogether. You will then have regular blood tests, for example once a year.
It’s important that you don’t simply stop taking ARBs because your blood pressure will quickly rise again. Always let your doctor, nurse or pharmacist know if you’re struggling because there could be other options you can try.
Angiotensin receptor blockers (ARBs) information sheet