Your doctor may prescribe ACE inhibitors or ARBs if you have:
There are systems in your body that work together to keep your blood pressure at a level high enough to get enough oxygen and nutrients around your body. ACE inhibitors and ARBs lower your blood pressure by acting on one of these systems; the renin-angiotensin-aldosterone system.
Sensors on your kidney can detect when your blood pressure drops too low. When this happens, a chemical called angiotensin I is released into your blood. On its own, angiotensin I doesn't have much effect. But when angiotensin I meets angiotensin-converting enzyme in the blood, it is converted into angiotensin II.
Angiotensin II narrows your blood vessels. It also acts on the adrenal glands to trigger the release of aldosterone. Aldosterone makes your body hold on to water. The extra volume of fluid in your blood and the narrowing of the blood vessels cause your blood pressure to rise. ACE inhibitors and ARBs work on these systems to act in the following ways.
Without angiotensin II, your blood vessels remain relaxed and the hormone aldosterone isn't released, so your blood pressure can be kept low.
ACE inhibitors and ARBs are only available on prescription from a doctor. They usually come as tablets, which you take once a day.
Many people with high blood pressure or heart problems need to take more than one medicine. ACE inhibitors may be prescribed in combination with other medicines, such as a diuretic or a calcium-channel blocker.
Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.
Your doctor may not prescribe ACE inhibitors or ARBs if you're pregnant or breastfeeding. If you are African-Caribbean and have high blood pressure, ARBs may not work so well for you, so your doctor may give you a different medicine.
ACE inhibitors and ARBs may be unsuitable if you have a problem with the arteries that supply your kidneys (renal artery stenosis). This is because they may affect the way your kidneys work. Also, if you have heart failure and your kidneys are affected as a result, ACE inhibitors and ARBs may not be suitable. However, if it's best to take these medicines, your doctor may ask you to have a blood test before you start them and then again in the first month of treatment. This is to check how well your kidneys are working.
Side-effects are the unwanted effects of taking a medicine. This section does not include every possible side-effect of ACE inhibitors and ARBs. Please read the patient information leaflet that comes with your medicine for more information.
The most common side-effects of ACE inhibitors and ARBs are low blood pressure and a reduction in kidney function. Other side-effects include:
In general, ARBs cause fewer side-effects than ACE inhibitors. If you have side-effects, it's important to talk to your doctor or the healthcare professional who prescribed your medicine before you stop taking it.
Some medicines can enhance the effects of ACE inhibitors and ARBs, resulting in very low blood pressure (hypotension). Check with your doctor or pharmacist before you take any other medicines or herbal remedies at the same time as ACE inhibitors or ARBs.
You may find herbal remedies helpful but it's important to remember that natural doesn't mean harmless. Herbal remedies contain active ingredients and may interact with other medicines or cause side-effects. Don't start taking any herbal remedies without speaking to your doctor or pharmacist first.
All medicines have a generic name. Many medicines also have one or more brand name. Generic names are in lower case, whereas brand names start with a capital letter. The main types of ACE inhibitors and ARBs are shown in the table.
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