Irbesartan belongs to a family of medicines known as angiotensin II receptor blockers. These medicines are used to lower high blood pressure and work by relaxing blood vessels. Irbesartan is also used to lower blood pressure and decrease the rate of the progression of kidney damage for patients with type 2 diabetes.

Angiotensin II is a chemical that the body releases to cause the constriction of blood vessels. Irbesartan blocks the action of angiotensin II, resulting in the relaxation of the blood vessels. This relaxation causes the blood pressure to decrease. The full effects of irbesartan are usually seen within about 4 weeks. It can be used alone or in combination with thiazide diuretics (water pills; e.g., hydrochlorothiazide).

This medication does not cure high blood pressure, but it does help to control it when it is taken regularly. Do not stop taking this medication without discussing the risks and benefits with your doctor.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The usual starting dose of irbesartan is 150 mg daily at approximately the same time each day. If you are taking other medication to reduce your blood pressure, your doctor may start you with a dose of 75 mg daily. The doctor may decide to increase the dose to 300 mg once a day if your blood pressure has not come down enough.

Irbesartan may be taken with or without food but should be taken in the same manner each day.

Make sure you follow your doctor's instructions about monitoring your blood pressure to ensure that you receive the maximum benefit from the medication.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

75 mg
Each white, oval, biconvex, film-coated tablet, debossed with "75" on one side contains 75 mg of irbesartan. Nonmedicinal ingredients: cellulose microcrystalline, croscarmellose sodium, hypromelose, lactose monohydrate, hydroxypropylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, silica colloidal anhydrous, talc, and titanium dioxide.

150 mg
Each white, oval, biconvex, film-coated tablet, debossed with "150" on one side contains 150 mg of irbesartan. Nonmedicinal ingredients: cellulose microcrystalline, croscarmellose sodium, hypromelose, lactose monohydrate, hydroxypropylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, silica colloidal anhydrous, talc, and titanium dioxide.

300 mg
Each white, oval, biconvex, film-coated tablet, debossed with "300" on one side contains 300 mg of irbesartan. Nonmedicinal ingredients: cellulose microcrystalline, croscarmellose sodium, hypromelose, lactose monohydrate, hydroxypropylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, silica colloidal anhydrous, talc, and titanium dioxide.

Do not take irbesartan if you:

• are allergic to irbesartan or any ingredients of the medication
• have experienced a serious allergic reaction to another angiotensin II receptor blocker (ARB) (e.g., candesartan, losartan, valsartan)
• have diabetes mellitus, kidney damage caused by diabetes, or severely reduced kidney function and are taking the medication aliskiren or an angiotensin-converting enzyme (ACE) inhibitor
• are pregnant
• are breast-feeding
• have galactose intolerance or glucose malabsorption (a rare hereditary disease)

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea
• dizziness
• drowsiness
• headache
• increased sensitivity of the skin to sunlight
• lightheadedness
• rash
• trouble sleeping
• unusual tiredness
• vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• back or leg pain, muscle cramps
• dizziness when rising from a sitting or lying position
• fainting
• fast heartbeat
• ringing in the ears
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of muscle damage (e.g., unexplained muscle pain, tenderness or weakness, or brown or discoloured urine)
• signs of too much potassium in the blood (e.g., muscle weakness, irregular heartbeat, general feeling of being unwell)
• swelling of the hands or feet
• symptoms of low blood sugar (e.g., cold sweat, cool pale skin, headache, fast heartbeat, weakness)
• symptoms of psoriasis flare up (e.g., painful, itchy skin, red patches, scales)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood sugar: Irbesartan can cause decreased levels of glucose in the blood. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

Drowsiness/reduced alertness: Irbesartan, like other medications for blood pressure, may cause dizziness and lightheadedness, especially if you have been taking a diuretic (water pill). This may affect your ability to drive or operate machinery. Avoid these and other activities until you have determined that this medication does not affect you in this way.

Heart disease: If you have a history of heart problems, such as a recent heart attack or stroke, narrowing of the heart valves (valvular stenosis) or other heart disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: Irbesartan may affect the function of the kidneys, especially for people who already have kidney problems. Certain people may be more likely to experience changes in kidney function (e.g., people with narrowed blood vessels in their kidneys, or those with severe congestive heart failure). The use of diuretics (water pills) or aliskiren may further increase risk of kidney problems for those at risk for this problem. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Low blood pressure: Occasionally, a larger-than-expected decrease in blood pressure occurs after taking irbesartan. In some cases, this happens after the first dose. It is more likely to occur if you take diuretics (water pills) or the medication aliskiren, have a reduced salt intake, are on dialysis, or are experiencing diarrhea or vomiting. Blood pressure should be monitored more often in these situations. If you have low blood pressure or are just starting to take this medication, move slowly from a reclining to an upright position to reduce the risk of dizziness.

Potassium levels: This medication may affect potassium levels in the blood, especially when used for heart failure, or when taken with other medications called ACE inhibitors or diuretics such as spironolactone. Your doctor will monitor your potassium levels while you are on this medication. Avoid using salt substitutes that contain potassium while you are taking irbesartan.

Pregnancy: Irbesartan can cause severe harm or death to a developing baby if it is taken during pregnancy. Therefore, this medication should not be taken by pregnant people. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if irbesartan passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: Older adults may be more likely to experience side effects of this medication.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.