There are systems in your body that work together to keep your blood pressure 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 in your kidneys 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 reacts with 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.
- ACE inhibitors block the action of ACE so that angiotensin I isn't converted to angiotensin II.
- ARBs block the action of angiotensin II by stopping it from interacting with your blood vessels and adrenal glands.
Without angiotensin II, your blood vessels remain more relaxed and the hormone aldosterone isn't released, so your blood pressure is lowered.
ACE inhibitors and ARBs are only available on prescription from a doctor. They usually come as tablets, which you take once or twice a day.
Many people with high blood pressure or heart problems need to take more than one medicine. Your doctor may prescribe ACE inhibitors 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’re African or 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 not be suitable if you have a narrowing of the arteries that supply your kidneys (renal artery stenosis). This is because they may affect the way your kidneys work. Your doctor may ask you to have a blood test before you start them and further tests while you’re taking them. 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. You may also have a persistent dry cough with ACE inhibitors (but not commonly with ARBs).
Other side-effects include:
- skin rashes
- cold-like symptoms
- feeling sick or vomiting
- diarrhoea or constipation
In general, ARBs cause fewer side-effects than ACE inhibitors. Your doctor may offer ARBs if you get a cough or other side-effects with ACE inhibitors. If you have side-effects, talk to your doctor or the healthcare professional who prescribed your medicine.
Some medicines can enhance the effects of ACE inhibitors and ARBs, resulting in very low blood pressure (hypotension). Other medicines that cause a rise in the potassium level in the blood can also cause problems if taken together with ACE inhibitors and ARBs. Check with your doctor or pharmacist before taking any other medicines.
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.
Generic name Examples of common brand names ACE inhibitors captopril Capoten, Capozide* cilazapril Vascase enalapril Innovace, Innozide* imidapril Tanatril lisinopril Zestril, Carace Plus*, Zestoretic* moexipril Perdix perindopril erbumine Perindopril perindopril arginine Conversyl Arginine, Conversyl Arginine Plus* quinapril Accupro, Accuretic* ramipril Tritace, Triapin** trandolapril Gopten, Tarka** Angiotensin II receptor blockers azilsartan Edarbi candesartan Amias eprosartan Teveten irbesartan Aprovel, CoAprovel* losartan Cozaar, Cozaar-Comp* olmesartan Olmetec, Olmetec Plus*, Sevikar**, Sevikar HCT *** telmisartan Micardis, Micardis Plus* valsartan Diovan, Co-Diovan*, Exforge**
*with a diuretic; ** with calcium-channel blocker, *** with calcium-channel blocker and diuretic
Can I drink alcohol when I’m taking ACE inhibitors or angiotensin II receptor blockers (ARBs)?
If you've been prescribed an ACE inhibitor or an ARB, you should always check with your doctor whether it is safe for your to drink alcohol and how much.
ACE inhibitors and ARBs are mainly used to treat high blood pressure. These medicines block the actions of chemicals released by your kidneys that work to increase your blood pressure. Alcohol temporarily relaxes your blood vessels and slows your heart rate (although over a longer period alcohol will increase your blood pressure).
If you’re taking ACE inhibitors or ARBs, alcohol can temporarily enhance the effects and lower your blood pressure too much. Low blood pressure is a common side-effect in people taking ACE inhibitors and ARBs. Drinking alcohol makes this even more likely to happen.
You may feel dizzy, light-headed and your blood pressure may drop to a point where you faint or have a heart attack.
Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.
Do angiotensin II receptor blockers (ARBs) increase your risk of cancer?
No, ARBs don't increase your risk of cancer.
In 2010, a study suggested that people taking ARBs had a slightly increased risk of cancer compared to those not taking the medicine. The researchers had looked at information from five clinical trials.
Since then, there have been three more reviews of all relevant clinical trials, including data from many more studies and thousands of patients. All three found no evidence to suggest ARBs increased the risk of cancer.
If you're taking ARBs and have any concerns, it's important to talk to your doctor or the healthcare professional who prescribed your medicine.
How do ACE inhibitors help people with diabetes?
If you have diabetes, ACE inhibitors help to protect your kidneys from becoming damaged as a result of your condition.
If you have diabetes, you’re at higher risk of getting kidney disease. This is because the high levels of glucose associated with diabetes can damage the small blood vessels in your kidneys.
High blood pressure can cause further damage to your kidneys. So if you have diabetes, it is especially important to keep your blood pressure under control. Doctors prescribe ACE inhibitors to control blood pressure in people with diabetes. This is because they seem to offer better protection against kidney disease than other medicines for high blood pressure.
If you have diabetes, your doctor will prescribe an ACE inhibitor or an angiotensin II receptor blocker if tests show you have early signs of kidney disease or high blood pressure.
Why does my age affect whether I am prescribed an angiotensin-converting enzyme (ACE) inhibitor?
ACE inhibitors may be less effective at reducing blood pressure in people over 55 compared to younger people. If you’re aged 55 or over, your doctor will try to control your blood pressure with another medicine first. This is usually a calcium-channel blocker.
ACE inhibitors seem to be better at lowering blood pressure in younger people. This may be because younger people with high blood pressure have a higher level of a chemical called renin in their bodies. Your body needs renin to make angiotensin I – which is converted into angiotensin II. It is the effects of angiotensin II that raise your blood pressure.
Medicines such as ACE inhibitors that affect the renin-angiotensin system are therefore thought to have a better effect in younger people.
ACE inhibitors are also not as effective at lowering blood pressure in African or Caribbean people. This is because people from these ethnic groups tend to have lower levels of renin. Renin is an enzyme made by the kidneys. It controls how much sodium and potassium is in your blood, keeping your blood pressure at the right level.
If you have high blood pressure and are over 55 or are African or Caribbean, your doctor may prescribe a diuretic or a calcium-channel blocker. If you don't respond to this medicine, he or she may then also prescribe an ACE inhibitor.
- Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. www.medicinescomplete.com, accessed 11 November 2013
- Rang HP, Dale MM, et al. Rang and Dale’s Pharmacology. 6th ed. Edinburgh: Churchill Livingstone Elsevier; 2007: 303–4
- Hypertension: Clinical management of primary hypertension in adults. National Institute for Health and Care Excellence (NICE), 2011. www.nice.org.uk
- Captopril. Interactions. Medscape. www.emedicine.medscape.com, accessed 14 November 2013
- Drug cabinet: ACE inhibitors. British Heart Foundation. www.bhf.org.uk, accessed 14 November 2013
- Diabetic Nephropathy. Medscape. www.emedicine.medscape.com, published 6 June 2012
- Hypertension. Medscape. www.emedicine.medscape.com, published 7 October 2013
- Diabetes – type 1. NICE Clinical Knowledge Summaries. cks.nice.org.uk, published December 2010
- Ethanol toxicity. Medscape. www.emedicine.medscape.com, published 5 June 2013
- Sipahi I, Debanne SM, Rowland DY, et al. Angiotensin-receptor blockade and risk of cancer: meta-analysis of randomised controlled trials. Lancet Oncol 2010; 11(7):627–36. doi: 10.1016/S1470-2045(10)70106
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