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

Captopril belongs to the group of medications known as ACE inhibitors. It is used to treat high blood pressure, congestive heart failure, and diabetic nephropathy (kidney problems caused by diabetes). It works by relaxing blood vessels and making the heart pump more efficiently.

Captopril may be used in addition to other blood pressure medications, such as a diuretic (water pill) like hydrochlorothiazide, when one medication has not been found to satisfactorily control blood pressure or congestive heart failure.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. 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.

How should I use this medication?

An initial low dose of 6.25 mg may be recommended to see if side effects develop.

The usual recommended doses range from 12.5 mg 3 times daily to 150 mg 3 times daily as prescribed by your doctor. Smaller doses may be used at the beginning of treatment depending on circumstances. The dose of captopril to control blood pressure does not usually go above 50 mg 3 times daily. The maximum dose of captopril is 450 mg daily in 3 divided doses.

Captopril should be taken 1 hour before meals.

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 to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next 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.

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.

What form(s) does this medication come in?

This medication is available as 12.5 mg, 25 mg, 50 mg, and 100 mg tablets.

Who should NOT take this medication?

Captopril should not be taken by anyone who:

  • is allergic to captopril or to any of the ingredients of the medication
  • is pregnant
  • has experienced angioedema (a serious allergic reaction that causes the area around the face, throat, and tongue to swell) after taking any of the class of medications known as ACE inhibitors (e.g., captopril, enalapril, fosinopril, lisinopril, etc.)

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.

  • cough (dry, persistent)
  • diarrhea
  • headache
  • loss of sense of taste
  • nausea
  • unusual tiredness

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

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

  • abdominal pain, abdominal distention
  • chest pain
  • dizziness, lightheadedness, or fainting (signs of low blood pressure)
  • fever, nausea, or vomiting
  • joint pain
  • skin rash (with or without itching)
  • Signs of too much potassium in the body:

  • confusion
  • irregular heartbeat
  • nervousness
  • numbness or tingling in the hands, feet, or lips
  • shortness of breath or difficulty breathing
  • weakness or heaviness in the legs

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

  • difficulty swallowing or breathing (sudden)
  • fever and chills
  • hoarseness
  • signs of angiodema (e.g., swelling of the face, mouth, hands, or feet)
  • stomach pain, itching of the skin, or yellow eyes or skin

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?


February 4, 2014

Health Canada has issued new restrictions concerning the use of captopril. To read the full Health Canada Advisory, visit Health Canada's web site at

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.

Angioedema: Angioedema (a serious allergic reaction that causes the area around the throat and tongue to swell) may occur with the use of ACE inhibitors, including captopril. This occurs for about 1 in 1,000 people. If you experience swelling of the face, tongue, or throat, stop taking captopril at once and seek immediate medical attention. People who have had angioedema caused by other substances may be at increased risk of angioedema while taking an ACE inhibitor.

Fluid and electrolyte levels: Increases in blood levels of potassium occur for a small percentage of people who take captopril. This rarely causes problems, but your doctor should monitor your potassium levels. People with kidney disease or diabetes are at a higher risk of having increased blood potassium while taking captopril.

Infection: Report any signs of infection, such as sore throat or fever, to your doctor.

Kidney function: Changes in kidney function have been seen in certain people. The use of diuretics (water pills) may further increase risk of kidney problems in those at risk for this problem. Tell your doctor if you notice any decrease in urine production or increased swelling of the lower limbs (suggesting accumulation of fluid due to decreased urine production).

Liver disease: People with liver disease should be cautious while taking captopril, as it may worsen this condition and cause increased side effects.

Low blood pressure: Occasionally, blood pressure drops too low after taking captopril. This usually happens after the first or second dose or when the dose is increased. It is more likely to occur for those who take water pills, have a salt-restricted diet, are on dialysis, are suffering from diarrhea or vomiting, or have been sweating excessively and not drinking enough liquids. Get up slowly when rising from a sitting or lying down position. If low blood pressure causes you to faint or feel lightheaded, contact your doctor.

Pregnancy: Pregnant women should not take ACE inhibitors. If you discover you are pregnant, stop taking captopril at once and talk to your doctor.

Breast-feeding: Small amounts (1%) of captopril are passed from the mother to the infant in breast milk. The effect of this amount on the breast-fed child has not been determined. Speak to your doctor about whether you should breast-feed while taking this medication.

What other drugs could interact with this medication?

There may be an interaction between captopril and any of the following:

  • allopurinol
  • diuretics (water pills; e.g., hydrochlorothiazide, furosemide)
  • lithium
  • medications that increase potassium levels (e.g., potassium supplements, spironolactone, amiloride, triamterene, and salt substitutes containing potassium)
  • medications that lower blood pressure (e.g., beta-blockers such as propranolol or metoprolol)
  • nitrates (e.g., nitroglycerin, isosorbide dinitrate)
  • nonsteroidal anti-inflammatory medications (NSAIDs; e.g., ibuprofen, indomethacin, naproxen)
  • procainamide

If you are taking any of these 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.

Medications other than those listed above may interact with this medication. 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.

All material copyright MediResource Inc. 1996 – 2017. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source:

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