Medication Search: ACT Irbesartan/HCT

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ACT Irbesartan/HCT

Common Name:

irbesartan - hydrochlorothiazide


How does this medication work? What will it do for me?

This combination product contains 2 medications: irbesartan and hydrochlorothiazide. It is used to reduce high blood pressure.

Irbesartan belongs to a class of medications called angiotensin II blockers. It helps to lower blood pressure by relaxing blood vessels.

Hydrochlorothiazide is a diuretic or "water pill" that helps control blood pressure by getting rid of excess salt and water.

This medication is most often prescribed when other medications have been found to be ineffective or to have side effects, and when a person’s blood pressure is stabilized on irbesartan and hydrochlorothiazide taken individually. Under certain circumstances, it may be prescribed when there is a need to reduce severe high blood pressure quickly and the risk of continued high blood pressure is greater than the risk of side effects of the medication.

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.

What form(s) does this medication come in?

ACT Irbesartan/HCT is no longer being manufactured for sale in Canada. For brands that may still be available, search under irbesartan – hydrochlorothiazide. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

Treatment is started separately with irbesartan and hydrochlorothiazide. Once the best dose of each component (irbesartan and hydrochlorothiazide) has been determined, the combination tablets can be started. Irbesartan – hydrochlorothiazide is generally not started until the best dose of each ingredient has been determined.

The dose ranges from 1 tablet containing 150 mg irbesartan and 12.5 mg hydrochlorothiazide once daily to 1 tablet containing 300 mg irbesartan and 25 mg hydrochlorothiazide once daily. Tablets should be taken at approximately the same time each day, with or without food, and taken in the same manner each day.

When irbesartan-hydrochlorothiazide is used to reduce severe hypertension, the typical starting dose is 150 mg irbesartan and 12.5 mg hydrochlorothiazide once daily. After 2 to 4 weeks, the dose may be increased to 300 mg irbesartan and 25 mg hydrochlorothiazide once daily, if blood pressure is still high.

If you miss a dose, skip the missed dose and carry on as usual with your next dose. Do not take a double dose to make up for a missed dose. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

It is important to take this medication regularly and to follow your doctor"s instructions regarding monitoring blood pressure to ensure that you receive the maximum benefit from the medication.

Store this medication at room temperature and keep it in a dry place (not in the bathroom). Keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to irbesartan, hydrochlorothiazide, or any ingredients of the medication
  • are allergic to sulfonamide-containing medications
  • are breast-feeding
  • are pregnant or plan to become pregnant
  • have anuria (no urine flow)
  • have kidney disease as a complication of diabetes and are taking medications that belong to the family angiotensin-converting enzyme inhibitors (e.g., ramipril, enalapril)
  • have diabetes and are taking the medication aliskiren
  • have moderate-to-severe kidney disease and are taking the medication aliskiren
  • have galactose intolerance or glucose malabsorption (a rare hereditary disease)

What side effects are possible with this medication?

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.

  • back or leg pain
  • constipation
  • decreased appetite
  • decreased interest in sexual activity
  • diarrhea
  • dizziness
  • drowsiness
  • headache
  • increased sensitivity to sunlight
  • muscle cramps or spasms
  • nausea
  • rash
  • red patches on skin
  • restlessness
  • ringing in the ears
  • trouble sleeping
  • unusual tiredness
  • vomiting
  • weakness

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:

  • changes to the skin (e.g., lump, discoloured patch, or mole on the skin that changes slowly; firm red/pink lump; flat scaly patch)
  • enlarged glands in the mouth
  • pins-and-needles sensation in your fingers
  • rapid heartbeat
  • 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 infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
  • 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 low blood pressure (e.g., severe dizziness, lightheadedness, or fainting)
  • signs of low potassium levels in the blood (e.g., weakness, fatigue, muscle cramps, irregular heartbeat)
  • signs of muscle damage (e.g., unexplained muscle pain, tenderness or weakness, or brown or discoloured urine)
  • signs of psoriasis (e.g., patches of red skin, covered with scales; dry, cracked skin; swollen and painful joints)
  • symptoms of glaucoma (e.g., blurred vision, seeing halos of bright colours around lights, red eyes, increased pressure in your eyes, eye pain or discomfort)
  • symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
  • symptoms of low blood sugar (e.g., cold sweat, cool pale skin, headache, fast heartbeat, weakness)
  • symptoms of too much potassium in the body (e.g., muscle fatigue, weakness, difficulty moving, abnormal heart rhythms, nausea)
  • swelling of the hands, ankles, or feet
  • vision changes (e.g., sudden nearsightedness, blurred vision, eye pain, blind spots)

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)
  • signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
  • signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
  • sudden onset of difficulty breathing, shortness of breath, dizziness, fever

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.

Are there any other precautions or warnings for 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.

Allergic reaction: Some people who are allergic to sulfonamide medications also experience allergic reactions to hydrochlorothiazide. Before you take this medication, inform your doctor about any previous adverse reactions you have had to medications, especially to sulfonamide antibiotics or diabetes medications. Contact your doctor at once if you experience signs of an allergic reaction, such as skin rash, itching, difficulty breathing, or swelling of the face and throat.

Breathing: Hydrochlorothiazide has been linked to sudden breathing problems, starting shortly after taking the medication. If you experience shortness of breath, fever, or dizziness, seek immediate medical attention.

Cholesterol: An increase in cholesterol and triglycerides levels may occur when taking hydrochlorothiazide. Your doctor will monitor you for these changes while you are taking this medication.

Diabetes: Hydrochlorothiazide may make it more difficult to control diabetes. If you have diabetes, your doctor may ask that you monitor your blood sugar carefully while taking this medication.

An adjustment of your dose of antidiabetes medications, including insulin, may be needed.

Drowsiness/reduced alertness: Although irbesartan – hydrochlorothiazide is unlikely to affect alertness, occasionally dizziness or tiredness occurs when treating high blood pressure. Do not drive, operate machinery, or perform other potentially hazardous tasks until you have determined how this medication affects you.

Fluid and electrolyte balance: As with other diuretics, levels of electrolytes such as potassium, sodium, magnesium, and chloride can be affected by the use of this medication. Your doctor will periodically check to make sure your electrolytes are in balance.

Gout: Hydrochlorothiazide may increase the level of uric acid in the body, causing an attack of gout for people prone to this condition. If you have a history of gout or kidney stones, 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.

If you develop painful, warm, and swollen joints, contact your doctor as soon as possible.

Heart problems: Fluid and mineral changes in the body can affect several other medical conditions, including heart conditions. Irbesartan – hydrochlorothiazide can cause fluid to build up, increasing the work the heart must do to keep the blood circulating. If you have had a recent heart attack, or you have congestive heart failure, taking irbesartan – hydrochlorothiazide can make symptoms of these heart conditions worse. If you have a history of heart 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.

Low blood pressure: Occasionally, a larger-than-expected decrease in blood pressure occurs after taking this medication. In some cases, this happens after the first dose. It is more likely to occur if you take diuretics (water pills) such as 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 if you are just starting to take this medication, move slowly from sitting or lying down to an upright position to reduce the risk of dizziness.

Kidney function: Irbesartan – hydrochlorothiazide can cause changes to kidney function that may result in decreased kidney function, kidney failure, or possibly death. Certain people have experienced 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), nonsteroidal anti-inflammatory drugs (NSAIDs), or aliskiren may further increase risk of kidney problems for people already at risk for this problem. If you have reduced kidney function, renal artery stenosis (narrowing of blood vessels in the kidneys), or congestive heart failure, 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. If you have reduced kidney function, you may require lower doses of this medication.

Do not take this medication if you have severely decreased kidney function.

Liver function: On rare occasions, irbesartan can cause liver problems. If you have liver disease or decreased liver function, 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.

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.

Lupus: Hydrochlorothiazide may worsen the symptoms of systemic lupus erythematosus (SLE). If you have lupus, 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.

Sensitivity to sunlight: This medication may increase the sensitivity of the skin to sunlight, increasing the risk of sunburn. Avoid exposure to sunlight for long periods of time, particularly between the hours of 10 am and 2 pm, while you are taking this medication and for 7 days after completing treatment. Wear a broad-spectrum sunscreen and lip balm with an SPF of 30 or higher. If you notice any unusual skin rash or peeling, contact your doctor immediately.

Skin cancer: Recent studies of hydrochlorothiazide have connected long-term use of the medication with an increased risk of developing non-melanoma skin cancer. You should check your skin regularly for unusual skin changes. Talk to your doctor about any concerns you may have.

Vision changes: Hydrochlorothiazide occasionally causes vision changes, including increased eye pressure, myopia (nearsightedness), or an abnormal buildup of fluid in the eye. If you experience any eye symptoms, such as pain, blind spots or change in vision, contact your doctor as soon as possible. A history of allergy to penicillin or sulfonamides may increase the risk of developing eye problems from this medication.

Pregnancy: Irbesartan may cause severe harm to an unborn fetus and should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

People taking irbesartan – hydrochlorothiazide who are planning or trying to become pregnant should discuss other, more appropriate medications to control blood pressure with their doctor.

Breast-feeding: It is not known whether irbesartan passes into breast milk. Hydrochlorothiazide 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: Seniors may be more sensitive to the effects of this medication and may experience more side effects, even at normal adult doses.

What other drugs could interact with this medication?

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

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Last Updated: 12/07/2024