What is Irbesartan?

Irbesartan, sold under the brand names Avapro or Aprovel, among others, is a medication that helps to prevent the risk of strokes and is used to treat high blood pressure (hypertension), heart failure, and diabetic kidney disease. It is considered a reasonable initial treatment for high blood pressure and is taken by mouth. Versions are available as the combination irbesartan/hydrochlorothiazide^[1]. 

What MayoClinic says about Hypertension^[2]
High blood pressure (hypertension) is a common condition in which the long-term force of the blood against the artery walls is high enough that it may eventually cause health problems, such as heart disease. Blood pressure is determined both by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure.

A blood pressure reading is given in millimetres of mercury (mm Hg) and has two numbers:

• The top number (systolic pressure): The first, or upper, number measures the pressure in your arteries when your heart beats.
• The bottom number (diastolic pressure): The second, or lower, number measures the pressure in your arteries between beats.

You can have high blood pressure for years without any symptoms. Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke. Fortunately, high blood pressure can be easily detected. And once you know you have high blood pressure, you can work with your doctor to control it.

What the NHS says about Irbesartan^[3]

About Irbesartan
Irbesartan is an angiotensin receptor blocker (ARB) medicine widely used to treat high blood pressure.

It relaxes and widens your blood vessels and lowers your blood pressure to make it easier for your heart to pump blood around your body. It also helps to prevent future strokes, heart attacks and diabetic kidney disease. By reducing blood pressure, it controls the amount of protein you lose through your kidneys. Irbesartan is only available on prescription in the UK and comes as tablets.

If you have COVID-19 or think you might have it, keep taking your blood pressure medicines as usual.

There is no clear evidence that taking angiotensin receptor blockers (ARBs) like irbesartan will cause complications.

Key facts
Irbesartan is often used as a second-choice treatment. Your doctor may prescribe it if you had to stop taking a similar medicine (such as Ramipril) because it gave you a dry, irritating cough.

The main side effects of irbesartan are feeling dizzy, headaches, feeling or being sick, and low blood pressure hypotension) – but they’re usually mild and only last for a short time.

Tell your doctor if you get severe diarrhoea or vomiting from a stomach bug or illness. You may need to stop taking irbesartan for a while until you feel better.

Irbesartan is not recommended for women in pregnancy. Talk to your doctor if you’re trying to get pregnant or you’re already pregnant.

Irbesartan can make some people feel dizzy – especially when you first start taking it or after taking a bigger dose. If this happens to you, do not drive a car, ride a bike, or use tools or machinery. Also, drinking alcohol can increase the blood pressure-lowering effect of irbesartan, making you feel dizzy or light-headed. Do not drink alcohol if it makes you feel dizzy.

Taking Irbesartan^[4]

Who can take it
Most adults aged 18 and over can take irbesartan. Your doctor may prescribe irbesartan if you’ve taken other medicines to lower your blood pressure called angiotensin converting enzyme (ACE) inhibitors in the past. You may have had to stop taking them because of side effects such as a dry, irritating cough. Medicines like these include Ramipril and Lisinopril.

Who may not be able to take irbesartan
Irbesartan is not suitable for some people. To make sure it’s safe for you, tell your doctor if you:

• have ever had an allergic reaction to irbesartan or any other medicine
• have diabetes
• have heart or kidney problems
• have recently had a kidney transplant
• have or have recently had diarrhoea, or you’re being sick (vomiting)
• are on a low salt diet
• have low blood pressure (hypotension)
• are trying to get pregnant, are already pregnant, or you are breastfeeding

How and when to take it
Always follow your doctor’s advice and the instructions that came with your medicine.

Your dose of irbesartan depends on why you need the medicine. You should take it how your doctor says.

The usual dose for both high blood pressure and diabetic kidney disease is 150mg to 300mg, taken once a day. If you are over 75, or you have liver or kidney problems, your dose may be lower.

Changes to your dose
After a few weeks, your doctor will check your blood pressure and ask you if you’re getting any side effects. You may also have blood tests to check how well your kidneys are working and the amount of potassium in your blood. Your doctor will then decide whether to change your dose of irbesartan.

If irbesartan does not lower your blood pressure, your doctor may want to increase your dose. If your blood pressure gets too low or you get side effects, your doctor may want to lower your dose.

How to take it
Take irbesartan tablets once a day. Your doctor may suggest that you take your first dose before bedtime because it can make you dizzy. After the very first dose, you can take irbesartan at any time of day, but try to take it at the same time every day.

You can take irbesartan tablets with or without food. Swallow the tablets whole with a drink of water.

How long to take it for
For high blood pressure and diabetic kidney disease, treatment with irbesartan is usually long-term, even for the rest of your life.

If you get ill while taking it
If you have very bad diarrhoea or are being sick (vomiting) for any reason, contact your doctor or a pharmacist. They’ll be able to advise you about what to do. They may lower your dose or recommend that you stop taking irbesartan until you’re better and can eat and drink normally again.

If you take contraceptive pills and are sick (vomiting) or have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet to find out what to do.

If you forget to take it
If you miss a dose of irbesartan, take it as soon as you remember. If you do not remember until the next day, skip the missed dose and take your next dose at the usual time. Do not take a double dose to make up for a forgotten one. If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

Stopping irbesartan
It’s important to talk to your doctor if you want to stop taking irbesartan. Stopping it may cause your blood pressure to rise and can increase your chances of having a heart attack or stroke.

Side Effects^[5]

Common Side Effects
Like all medicines, irbesartan can cause side effects, although not everyone gets them. Side effects often improve as your body gets used to the medicine.

The following common side effects of irbesartan happen in more than 1 in 100 people. There are things you can do to help cope with them:

• Feeling dizzy: If irbesartan makes you feel dizzy when you stand up, try getting up very slowly or remain sitting down until you feel better. If you begin to feel dizzy, lie down, so you do not faint, then sit until you feel better. Do not drive, ride a bike or use tools or machines if you feel dizzy.
• Headaches: Make sure you rest and drink plenty of fluids. Try not to drink too much alcohol. Ask your pharmacist to recommend a painkiller. Headaches should usually go away after the first week of taking irbesartan. Talk to your doctor if the headaches last longer than a week or are severe.
• Feeling sick (nausea): Try taking your tablets with or after a meal or snack. It may also help if you do not eat rich or spicy food.
• Being sick (vomiting): Take small, frequent sips of water to avoid dehydration. Signs of dehydration include urinating less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat vomiting without speaking to a pharmacist or doctor first. You may need to stop taking irbesartan for a while until you feel better. If you take contraceptive pills and you’re being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
• Diarrhoea: Drink plenty of water or squash to prevent dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling urine. If you get severe diarrhoea, tell your doctor. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor first. You may need to stop taking irbesartan for a while until you feel better. If you take contraceptive pills and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.

Pain in your joints or muscles: If you get unusual muscle pain, weakness or tiredness which is not from exercise or physical work, talk to your doctor. You may need a blood test to check what might be causing it.

Talk to your doctor or pharmacist if the advice on how to cope does not help, and these side effects bother you or do not go away.

Serious Side Effects
It happens rarely, but some people have serious side effects after taking irbesartan.

Call a doctor or contact 111 now if:

• The whites of your eyes turn yellow, or your skin turns yellow (although this may be less obvious on brown or black skin) – this can be a sign of liver problems.
• You are paler than usual, feel tired, faint or dizzy, have purple spots, or any sign of bleeding, a sore throat and high temperature – these can be signs of blood or bone marrow disorder.
• You feel weak, have an irregular heartbeat, pins and needles and muscle cramps – these can be signs of changes in the potassium levels in your blood.

Go to https://111.nhs.uk or call 111.

Serious Allergic Reaction
In rare cases, irbesartan may cause a serious allergic reaction (anaphylaxis).

Immediate action required: Call 999 or go to A&E now if:

• you get a skin rash that may include itchy, red, swollen, blistered or peeling skin,
• you’re wheezing,
• you get tightness in the chest or throat,
• you have trouble breathing or talking,
• your mouth, face, lips, tongue or throat start swelling, you could be having a serious allergic reaction and may need immediate treatment in the hospital.

Long-term side effects
Taking irbesartan for a long time can sometimes cause your kidneys not to work as well as they should. Your doctor will check how well your kidneys are working with regular blood tests.

Other side effects
The lists above are not all the side effects of irbesartan. For a full list, see the leaflet inside your medicines packet.

Information:
You can report any suspected side effects using the Yellow Card safety scheme.

Important Points
If irbesartan has been prescribed, take it even if you feel well, as you’ll still benefit from the medicine. Taking too much irbesartan can cause dizziness (due to low blood pressure) and changes in heart rate. The amount of irbesartan that can lead to an overdose varies from person to person.

Urgent advice: Contact 111 for advice now if:

• you take more than your prescribed dose of irbesartan
• Go to https://111.nhs.UK or call 111

If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.

Take the irbesartan packet or the leaflet inside it, plus any remaining medicine, with you.

Although irbesartan may be used to prevent kidney problems or treat people who have kidney problems, it may also rarely cause serious kidney problems or make them worse. Your doctor will check your kidney function while you are taking irbesartan. Tell your doctor right away if you have any signs of kidney problems, such as a change in the amount of urine.^[6]

Pregnancy, breastfeeding and fertility^[7]
Irbesartan is not recommended in pregnancy. It can reduce the level of fluid around your baby, particularly if you take it in the second and third trimesters. This can result in long-term damage to your baby’s kidneys and lungs and other problems.

If you’re already pregnant, stop taking irbesartan and talk to your doctor straight away. Usually, your doctor will be able to prescribe a different medicine that is safer to take during pregnancy. Irbesartan should always be stopped by the time you’re 12 weeks pregnant.

It’s important to use contraception if you’re taking irbesartan and carefully plan any pregnancy with your doctor or a specialist. They will review your medical condition and medicine before you get pregnant.

Most women stop taking irbesartan before getting pregnant, but some may continue up until they have a positive pregnancy test and then stop. Your doctor will discuss what’s best for you based on your condition and the risks and benefits of irbesartan.

Irbesartan and Breastfeeding
It might be OK to take irbesartan while breastfeeding but talk to your doctor or pharmacist first. It is best not to take irbesartan if your baby was born prematurely, but your doctor will help you decide.

It is not yet known how much irbesartan gets into breast milk. There is a very small risk that it could also lower your baby’s blood pressure. Until we know more about irbesartan in breastfeeding, your doctor might recommend a different medicine for you to take.

If you notice that:

• your baby is not feeding as well as usual,
• seems unusually sleepy,
• looks much paler than normal, or if you have any other concerns about your baby, then you should talk to your health visitor, midwife or doctor as soon as possible.

Irbesartan and Fertility
There’s no evidence to suggest that taking irbesartan reduces fertility in men or women. However, speak to a pharmacist or your doctor before taking it if you’re trying to get pregnant.

Non-urgent advice: Tell your doctor if you’re:

• trying to get pregnant
• pregnant
• breastfeeding

For more information about how angiotensin receptor blockers (ARBs) like irbesartan can affect you and your baby during pregnancy, visit the Best Use of Medicines in Pregnancy (BUMPS) website^[8].

Taking irbesartan with other medicines and herbal supplements^[9]

Cautions with other medicines
Some medicines may affect the way irbesartan works. Tell your doctor or pharmacist if you’re taking:

• other medicines to help lower your blood pressure, including aliskiren, enalapril, captopril, lisinopril or Ramipril
• painkillers such as ibuprofen, naproxen, diclofenac, celecoxib or etoricoxib or a high dose of aspirin for pain relief
• heparin, a medicine to reduce the risk of blood clots
• medications that make you urinate more (diuretics)
• lithium, a medicine for mental health problems
• spironolactone, a medicine to treat heart failure

Mixing irbesartan with herbal remedies and supplements
Tell your pharmacist or doctor if you’re taking potassium supplements or salt substitutes that contain potassium.

There’s very little information that is available about taking other herbal remedies and supplements with irbesartan. They’re not tested in the same way as pharmacy and prescription medicines.

Important: Medicine Safety

Tell your doctor or pharmacist if you’re taking any other medicines, including herbal remedies, vitamins or supplements.

What WebMD says about Irbesartan^[10]
Do not share irbesartan with others. Lifestyle changes such as stress reduction programs, exercise, and dietary changes may increase the effectiveness of this medication. Talk to your doctor or pharmacist about lifestyle changes that might benefit you. Laboratory and/or medical tests (such as kidney function and potassium levels) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

Storage
Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard irbesartan when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for any further advice.

Drug Interactions
When a medication works right, it boosts your health or helps you feel better. But a medication can bring on problems if it doesn’t mix well with something else you put into your body, like another medication, a certain food, or alcohol. When that happens, it’s called a drug interaction. It could make your important medications stop working, become less effective, or be too strong. It could also trigger side effects.

Interaction Checker
The more you learn about drug interactions, the better you’ll be able to avoid them. WebMD has an Interaction Checker^[11], which, although quite innovative, should be used with caution: it should NOT be used as a substitute for the advice of an appropriately qualified doctor or other health care provider.  The information provided by the checker is for informational purposes only.

The Interaction Checker tool may not cover all possible drug interactions. Users with health questions or concerns should check with a doctor or appropriate health provider. WebMD says that although they attempt to provide accurate and up-to-date information, no guarantee is made to that effect.

Further Points to note
The Product Leaflet for irbesartan contains further^[12] informational and cautionary points, which users should note:

• Do not take irbesartan if you have diabetes or impaired kidney function, and you are treated with a blood pressure-lowering medicine containing aliskiren^[13].
• Talk to your doctor or pharmacist if you are due to have an operation (surgery) or if you are to be given anaesthetics.
• Children and adolescents should not use Irbesartan because the safety and efficacy of the medication have not yet been fully established.
• If you already take: potassium supplements, salt substitutes containing potassium, potassium-sparing medicines (such as certain diuretics), or medicines containing lithium^[14], before taking irbesartan, you may need to have blood checks.
• Irbesartan can be taken with or without food and should be taken at about the same time each day.
• It can take 1-2 weeks for irbesartan to lower blood pressure, with the maximal effect occurring by 4-6 weeks after the start of therapy.
• Once prescribed for you, it is important to continue to take irbesartan until your doctor tells you otherwise.
• Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines.

Side Effects
The frequency of side effects listed below is defined using the following convention:

• Very Common: means it may affect more than 1 in 10 people: if you suffer from high blood pressure and type 2 diabetes with kidney disease, blood tests may show an increased potassium level.
• Common: means it may affect up to 1 in 10 people: dizziness, feeling sick or vomiting, fatigue – blood tests may show raised levels of an enzyme that measures the muscle and heart function (creatine kinase enzyme). In patients with high blood pressure and type 2 diabetes with kidney disease, dizziness when getting up from a lying or sitting position, low blood pressure when getting up from a lying or sitting position, pain in joints or muscles and decreased levels of a protein in the red blood cells (haemoglobin) were also reported.
• Uncommon: means it may affect up to 1 in 100 people: heart rate increased, flushing, cough, diarrhoea, indigestion or heartburn, sexual dysfunction or chest pain.

Picture Credit: “Better Results” by shainemata is marked with CC BY-NC 2.0.

Some undesirable effects have been reported since the marketing of irbesartan. Undesirable effects where the frequency is not known are: feeling of spinning, headaches, taste disturbance, ringing in the ears, muscle cramps, pain in joints and muscles, reduced number of platelets, abnormal liver function, increased blood potassium levels, impaired kidney function and inflammation of small blood vessels mainly affecting the skin known as leukocytoclastic vasculitis and severe allergic reactions (anaphylactic shock). Uncommon cases of jaundice (yellowing of the skin and whites of the eyes) have also been reported.

Caution: No advice is implied or given in articles published by us. This guide is for general interest only. It should never be used as a substitute for obtaining advice from your Doctor or other qualified clinician/medical practitioner. The facts are believed to be correct as at the date of publication, but there may be certain errors and omissions for which we cannot be responsible. The hyperlinks were valid at the date of publication.

Sources and Further Reading

• https://en.wikipedia.org/wiki/Irbesartan
• https://www.nhs.uk/medicines/irbesartan/about-irbesartan/
• https://www.webmd.com/drugs/2/drug-4720/irbesartan-oral/details
• https://www.webmd.com/interaction-checker/default.htm
• https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/symptoms-causes/syc-20373410
• https://www.fda.gov/drugs/special-features/high-blood-pressure-understanding-silent-killer
• https://patient.info/medicine/irbesartan-an-angiotensin-receptor-blocker-aprovel-ifirmasta-sabervel
• https://www.nice.org.uk/guidance/ng136
• https://www.nice.org.uk/guidance/ng136/chapter/recommendations#diagnosing-hypertension
• Books on Hypertension at Amazon: https://www.amazon.co.uk/s?k=hypertension&i=stripbooks
• https://www.health.harvard.edu/a_to_z/high-blood-pressure-hypertension-a-to-z

Picture Credit: “Jim Depuy, pharmacist checking in an order” by safoocat is marked with CC BY-NC-ND 2.0.

1. Source: Wikipedia at: https://en.wikipedia.org/wiki/Irbesartan ↑

2. Source: https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/symptoms-causes/syc-20373410 ↑

3. Source: https://www.nhs.uk/medicines/irbesartan/about-irbesartan/ © Crown Copyright acknowledged ↑

4. Source: https://www.nhs.uk/medicines/irbesartan/who-can-and-cannot-take-irbesartan/ © Crown Copyright acknowledged ↑

5. Source: https://www.nhs.uk/medicines/irbesartan/side-effects-of-irbesartan/ © Crown Copyright acknowledged ↑

6. Source: https://www.webmd.com/drugs/2/drug-4720/irbesartan-oral/details ↑

7. Source: https://www.nhs.uk/medicines/irbesartan/pregnancy-breastfeeding-and-fertility-while-taking-irbesartan/ © Crown Copyright acknowledged ↑

8. At: http://www.medicinesinpregnancy.org/Medicine–pregnancy/Angiotensin-II-receptor-antagonists/ ↑

9. Source: https://www.nhs.uk/medicines/irbesartan/taking-irbesartan-with-other-medicines-and-herbal-supplements/ © Crown Copyright acknowledged ↑

10. Source: https://www.webmd.com/drugs/2/drug-4720/irbesartan-oral/details ↑

11. Source: https://www.webmd.com/interaction-checker/default.htm ↑

12. ‘Further’ in this context means ‘further to the points made previously in this document’. The Leaflet (Milfarm) viewed was revised in January 2019. ↑

13. ‘Aliskiren’ is the first in a class of drugs called direct renin inhibitors. It is used for essential hypertension. While used for high blood pressure, other better studied medications are typically recommended due to concerns of higher side effects and less evidence of benefit. Source: Wikipedia. See also: https://bnf.nice.org.uk/drug/aliskiren.html ↑

14. ‘Lithium’ is a type of medicine known as a ‘mood stabiliser’. ↑