Captopril (Capoten)

Pronunciation: KAP-toe-pril.

Generic name
captopril
Drug class
Angiotensin-converting enzyme (ACE) inhibitor
Form
Tablets (12.5 mg, 25 mg, 50 mg, 100 mg) and oral solution (5 mg/mL or 5 mg and 25 mg per 5 mL, depending on market)
Route
Oral
Legal status
Prescription-only medicine in every market confirmed this session (United States, United Kingdom, European Union, Canada, Australia, New Zealand); always check your own country and product label.

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Capoten (captopril) (5) · Full directory

What captopril is and how it works

Captopril is one of the original ACE (angiotensin-converting enzyme) inhibitors, a class of medicines that relax blood vessels by blocking the production of a hormone (angiotensin II) that narrows them. It is a short-acting medicine usually taken two or three times a day, an hour before meals. (1) (4) (2)

Captopril is used for high blood pressure, heart failure, to improve survival and reduce heart-failure hospitalisations after a heart attack with reduced heart-pumping function, and for kidney protection in type 1 diabetes with protein in the urine. The single most important safety fact, confirmed across every market checked, is that ACE inhibitors like captopril can seriously harm or even cause the death of a developing baby if taken during pregnancy, especially in the second and third trimesters -- the US FDA label and Health Canada's product monograph both carry this as a formal boxed warning, while the UK and EU labels reviewed state it as an explicit contraindication for the second and third trimesters. Anyone who could become pregnant should discuss this with their prescriber before starting captopril and contact their clinician urgently if they become pregnant while taking it.

Mechanism of action: how captopril works

Captopril is a specific competitive inhibitor of angiotensin-converting enzyme (ACE), the enzyme that converts angiotensin I to angiotensin II, a potent vasoconstrictor that also stimulates aldosterone secretion. By inhibiting ACE, captopril reduces peripheral vascular resistance and blood pressure; ACE is identical to 'bradykininase', so captopril may also raise levels of the vasodilator bradykinin, which may contribute to its therapeutic effect. (1) (6)

What captopril is used for

High blood pressure (hypertension)

Used alone or with other antihypertensive medicines, especially thiazide-type diuretics, to lower blood pressure. (1) (4) (6)

Heart failure

Used together with a diuretic (and digitalis where appropriate) to treat congestive heart failure. (1) (2) (4)

After a heart attack (left ventricular dysfunction)

Used to improve survival, delay the onset of symptomatic heart failure, and reduce heart-failure-related hospitalisations in clinically stable patients whose heart-pumping function (ejection fraction) is reduced to 40% or less following a myocardial infarction. (1) (2) (4) (6)

Diabetic kidney disease (diabetic nephropathy)

Used to slow the progression of kidney disease and reduce the risk of serious outcomes (such as needing dialysis or a transplant, or death) in people with type 1 insulin-dependent diabetes, protein in the urine, and diabetic eye disease (retinopathy). (1) (4) (6)

Before taking captopril

Do not take / not appropriate for

  • Do not take captopril if you have a known hypersensitivity (allergy) to captopril or any other ACE inhibitor, including a previous episode of angioedema (swelling) while taking any ACE inhibitor. (all countries) (1) (4)
  • Do not take captopril if you have hereditary or idiopathic angioedema. (United Kingdom, European Union, New Zealand) (2) (6)
  • Do not take captopril during the second or third trimester of pregnancy -- this is an explicit contraindication in the UK/EU labels reviewed, and the equivalent boxed-warning instruction in the US and Canadian labels reviewed. (all countries) (2) (1) (4)
  • Do not combine captopril with aliskiren if you have diabetes or kidney impairment (GFR below 60 mL/min). (all countries) (6) (2)
  • Do not start captopril within 36 hours of your last dose of sacubitril/valsartan. (all countries) (6) (2)

Tell your clinician about

  • If you are pregnant, think you might be pregnant, or are planning a pregnancy -- this is critical to discuss before starting captopril; contact your clinician urgently if you become pregnant while taking it.
  • If you have kidney disease or reduced kidney function, especially with collagen vascular disease (such as lupus or scleroderma), since the risk of a rare but serious blood-cell problem (neutropenia) is substantially higher.
  • If you have ever had swelling of the face, lips, tongue, or throat (angioedema), even from a different medicine.
  • If you are on dialysis, especially with certain high-flux membranes, or are due to have LDL apheresis.
  • If you are due to have venom (e.g. bee or wasp sting) desensitisation treatment.
  • If you take potassium supplements, potassium-sparing diuretics, or salt substitutes containing potassium.
  • If you take lithium, NSAIDs (including COX-2 inhibitors), other blood-pressure medicines that act on the same hormone system (ARBs, aliskiren), or sacubitril/valsartan.
  • If you are on a low-salt diet, take diuretics, or have recently had vomiting or diarrhoea, since this increases the risk of a large blood-pressure drop after your first dose.
  • Any other medicines you take.
(1) (2) (4) (6)

How to take captopril

  • Take captopril one hour before meals, since food can reduce how much of the dose your body absorbs.
  • Your prescriber will usually start you on a low dose and increase it gradually, especially if you have heart failure, kidney impairment, are on diuretics, or are elderly.
  • Take captopril at the same times each day, exactly as prescribed.
  • Do not stop taking captopril or change your dose without talking to your prescriber first, even if you feel well -- but contact your clinician urgently, rather than simply stopping on your own, if you become pregnant.
  • If you have heart failure, increase your physical activity gradually rather than suddenly, on your prescriber's advice.
(6)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

This dossier's sources did not provide specific patient-facing missed-dose instructions for captopril. If you miss a dose, contact your pharmacist or prescriber for advice rather than doubling your next dose.

Overdose

This dossier's sources focused on dosing and safety monitoring rather than detailed overdose management. If an overdose is suspected, seek urgent medical attention or contact your local poison control service immediately, since captopril overdose can cause a severe fall in blood pressure.

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Dry, persistent cough.

What to notice: Dry, persistent cough.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Dizziness or lightheadedness, especially after the first few doses.

What to notice: Dizziness or lightheadedness, especially after the first few doses.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Changed or reduced sense of taste (usually reversible within 2-3 months).

What to notice: Changed or reduced sense of taste (usually reversible within 2-3 months).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Skin rash, sometimes with itching, usually in the first four weeks of treatment.

What to notice: Skin rash, sometimes with itching, usually in the first four weeks of treatment.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Nausea, vomiting, diarrhoea, or stomach upset.

What to notice: Nausea, vomiting, diarrhoea, or stomach upset.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Rapid or irregular heartbeat.

What to notice: Rapid or irregular heartbeat.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Tiredness, headache, or trouble sleeping.

What to notice: Tiredness, headache, or trouble sleeping.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Fetal toxicity in pregnancy — boxed_warning

Symptoms: No symptoms in the mother; the risk is to the developing baby.

Action: Contact your clinician urgently as soon as pregnancy is detected or suspected, so they can discuss stopping captopril and switching to a pregnancy-appropriate alternative -- drugs that act on the renin-angiotensin system, including captopril, can cause serious injury and death to a developing baby, especially in the second and third trimesters. This is a formal boxed warning on the current US and Canadian labels, and an explicit contraindication in the UK/EU labels reviewed. (1) (4) (2)

Angioedema (swelling of the face, lips, tongue, or throat) — high caution

Symptoms: Swelling of the face, lips, tongue, or throat, difficulty swallowing or breathing, or hoarseness.

Action: Seek emergency medical attention immediately -- swelling involving the tongue, throat, or voice box can block the airway and be fatal. This risk is higher in Black patients, and anyone with a past ACE-inhibitor-related angioedema should not take any ACE inhibitor again. (1) (4) (6)

Neutropenia/agranulocytosis (low white blood cell count) — high caution, especially with kidney impairment

Symptoms: Fever, sore throat, mouth infections, or other signs of infection.

Action: Report any signs of infection to your clinician promptly for a blood test. This risk is substantially higher in people with reduced kidney function or collagen vascular disease (such as lupus or scleroderma) -- your prescriber may check your white blood cell count regularly, especially in the first three months of treatment, if you have kidney impairment. (1) (4)

First-dose or excessive low blood pressure (hypotension) — moderate to high caution

Symptoms: Severe dizziness, lightheadedness, or fainting, particularly after your first dose or a dose increase.

Action: Contact your clinician if this happens or is severe. Your prescriber will usually start you on a low dose, particularly if you have heart failure, are on diuretics, or are on a low-salt diet, to reduce this risk. (1) (6)

High potassium levels (hyperkalemia) — moderate caution

Symptoms: Muscle weakness, tingling, or an irregular heartbeat -- often no symptoms until found on a blood test.

Action: Your prescriber may monitor your blood potassium periodically, especially if you have kidney problems, diabetes, or take potassium supplements or potassium-sparing diuretics. (1) (2)

Rare liver injury (hepatic failure) — important safety information

Symptoms: Yellowing of the skin or eyes (jaundice), or marked fatigue.

Action: Contact your clinician promptly -- this is a rare syndrome that can start with jaundice and, rarely, progress to serious or fatal liver failure; your prescriber will stop captopril and arrange follow-up if this occurs. (1) (2)

Protein in the urine (proteinuria) — moderate caution

Symptoms: Usually no symptoms; found on a urine test.

Action: Your prescriber may check your urine periodically, especially in the first nine months of treatment or if you have existing kidney disease or take higher doses. (1) (4)

Severe allergic (anaphylactoid) reactions during desensitisation or dialysis — important safety information, population-specific

Symptoms: Facial flushing, swelling, or a sudden drop in blood pressure during venom desensitisation treatment or certain types of dialysis.

Action: Tell your clinician you are taking captopril before any planned venom (e.g. bee/wasp sting) desensitisation treatment or high-flux membrane dialysis, since ACE inhibitors have been linked to severe reactions in these specific situations. (1) (6)

Interactions

  • Potassium-sparing diuretics, potassium supplements, or potassium-containing salt substitutes: increased risk of high potassium levels; do not use without consulting your prescriber. (1)
  • NSAIDs, including COX-2 inhibitors: may reduce captopril's blood-pressure-lowering effect and increase the risk of kidney problems, particularly in elderly, volume-depleted, or kidney-impaired patients. (1)
  • Other medicines acting on the same hormone system (ARBs, aliskiren): combining with captopril increases the risk of low blood pressure, high potassium, and kidney problems; aliskiren should not be combined with captopril in people with diabetes or reduced kidney function. (1) (6)
  • Sacubitril/valsartan: must not be started within 36 hours of stopping captopril, and vice versa, due to increased angioedema risk. (6)
  • Lithium: captopril can raise lithium levels and increase the risk of lithium toxicity; monitoring is recommended. (1)
  • Diuretics: captopril's blood-pressure-lowering effect and hypotension risk are increased with diuretics, especially when started recently or at high doses. (1)
  • Injectable gold: rare nitritoid reactions (facial flushing, nausea, vomiting, low blood pressure) reported with concurrent ACE inhibitor use. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Captopril must not be used during the second or third trimester of pregnancy, and first-trimester use is not recommended unless clearly necessary, since it can cause serious injury or death to a developing baby. Contact your clinician urgently if you become pregnant while taking captopril. (1) (2) (3) (4) (5) (6)

Breastfeeding

Captopril passes into breast milk at low concentrations (approximately 1% of maternal blood levels); your clinician will weigh the potential risk to a nursing infant against the importance of the medicine to you. (1) (2) (3) (4) (5) (6)

Children

Safety and effectiveness in children have not been established; captopril is used in children only if other blood-pressure treatments have not been effective, since infants (especially newborns) may be more sensitive to its blood-pressure-lowering effects. (1) (2) (3) (4) (5) (6)

Elderly

No specific dose recommendation beyond general caution; elderly patients may be more sensitive to blood-pressure and kidney effects, so treatment often starts at a lower dose. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

This dossier's sources did not detail specific hepatic dose-adjustment guidance for captopril beyond the general warning that a prescriber will typically advise stopping captopril if jaundice or a significant rise in liver enzymes occurs, since this can signal a rare but serious liver reaction. (1) (2) (3) (4) (5) (6)

Renal_impairment

A lower starting dose and slower dose titration are recommended, since captopril is excreted more slowly when kidney function is reduced; captopril is removed by haemodialysis, and a loop diuretic is generally preferred over a thiazide if a diuretic is needed. (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Pregnancy test and contraception discussion where relevant.
  • Baseline kidney function and electrolytes (including potassium).
  • Baseline blood pressure, particularly if starting from a diuretic or low-salt diet.
  • Assessment of collagen vascular disease history in patients with reduced kidney function, given the substantially higher neutropenia risk.

During treatment

  • White blood cell and differential counts at baseline and approximately every two weeks for about three months, then periodically, in patients with impaired kidney function.
  • Periodic kidney function and blood potassium monitoring.
  • Urine protein checks periodically, especially in the first nine months or with higher doses.
  • Blood pressure monitoring, especially after the first dose or a dose increase.
  • Prompt reporting of any signs of infection, swelling of the face/lips/tongue/throat, or persistent cough.
(1) (4)

Storage

Store at room temperature as directed on the packaging, protected from moisture, and keep out of the reach of children.

Study the drug class: ACE inhibitors

Professional information

Clinician-facing context only, sourced from the current US FDA/DailyMed prescribing information, UK EMC SmPC, France's ANSM database, Health Canada product monograph, Australia's TGA ARTG registration, and New Zealand's Medsafe data sheet reviewed for this dossier; verify against the current full label for the specific product before prescribing.

United States, Canada

Indication: Hypertension, heart failure, post-MI left ventricular dysfunction, diabetic nephropathy

Dose summary: Hypertension: 12.5-150 mg/day in divided doses; heart failure/post-MI: low starting dose (6.25-12.5 mg) titrated to target (e.g. 50 mg t.i.d. post-MI); 12.5, 25, 50, 100 mg tablets.

Renal context: Retention occurs with renal impairment; dosage reduction and monitoring recommended. (1) (4)

United Kingdom, European Union, Australia, New Zealand

Indication: Same core indication set (hypertension, heart failure, MI, diabetic nephropathy), per the UK SmPC, France's ANSM listing, Australia's TGA registration, and New Zealand's data sheet reviewed

Dose summary: Dosing matches the US/Canada pattern; New Zealand data sheet specifies hypertension starting dose 12.5 mg, usual maximum 50 mg twice daily in mild-moderate disease (up to 75 mg twice daily in severe/refractory cases); heart failure maintenance 25-75 mg twice daily (max 150 mg/day); diabetic nephropathy 75-100 mg/day in divided doses.

Renal context: Lower starting dose and slower titration in renal impairment; loop diuretic preferred over thiazide; removed by haemodialysis. (6) (2)

Mechanism of action

Hepatic guidance

This dossier's sources did not detail specific hepatic dose-adjustment guidance beyond the general instruction to discontinue captopril and follow up if jaundice or marked hepatic enzyme elevation occurs.

Overdose note

This dossier's sources did not detail specific overdose management guidance for captopril beyond general supportive care and blood-pressure support principles. (1) (6)

Frequently asked questions

Is captopril (Capoten) available in the US, UK, EU, Canada, Australia, and New Zealand?

Yes, confirmed authorised via direct regulator sources in all six markets: the United States (DailyMed/FDA), United Kingdom (EMC SmPC), the European Union (France's ANSM database, since captopril's authorisation predates the EMA's centralised procedure), Canada (Health Canada product monograph), Australia (TGA ARTG), and New Zealand (Medsafe). (1) (2) (3) (4) (5) (6)

Does captopril carry a boxed warning?

Yes -- captopril carries a genuine, class-wide FDA boxed warning for fetal toxicity: when pregnancy is detected, Capoten should be discontinued as soon as possible, since drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. Health Canada's product monograph carries the same substantive warning in its own boxed 'Serious Warning' section. The UK and EU labels reviewed express the same clinical fact as an explicit contraindication for the second and third trimesters of pregnancy, rather than a formatted boxed warning. (1) (4) (2)

What is captopril used for?

Captopril is used for high blood pressure, heart failure (with a diuretic), improving survival and reducing hospitalisations after a heart attack with reduced heart-pumping function, and slowing kidney disease progression in type 1 diabetes with protein in the urine. (1) (4) (2)

What are the most serious risks of taking captopril?

The most serious, well-documented risks are fetal toxicity in pregnancy (boxed warning), angioedema (swelling that can affect the airway and be fatal, with a higher rate in Black patients), neutropenia/agranulocytosis (a rare but serious drop in white blood cells, especially with reduced kidney function), first-dose low blood pressure, high potassium levels, and rare liver injury. Regular monitoring and blood tests are used to catch problems early. (1) (4) (2)

What is the mechanism of action of captopril?

Captopril is a specific competitive inhibitor of angiotensin-converting enzyme (ACE), the enzyme that converts angiotensin I to angiotensin II, a potent vasoconstrictor that also stimulates aldosterone secretion. By inhibiting ACE, captopril reduces peripheral vascular resistance and blood pressure; ACE is identical to 'bradykininase', so captopril may also raise levels of the vasodilator bradykinin, which may contribute to its therapeutic effect. (1) (6)

What is the generic name of Captopril (Capoten)?

The generic name is captopril. (1) (2)

What class of drug is captopril?

Captopril (Capoten) is classed as: Angiotensin-converting enzyme (ACE) inhibitor. (1) (2)

References

  1. CAPOTEN (Captopril Tablets, USP) -- full prescribing informationDailyMed (U.S. National Library of Medicine) / FDA drug label archive -- FDA-approved prescribing information · United States · dated 2012-01-01 · accessed 2026-07-31 · source 1
  2. Captopril 25mg/5ml Oral Solution -- SmPC (Martindale Pharma)electronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics · United Kingdom · dated 2018-04-24 · accessed 2026-07-31 · source 2
  3. CAPTOPRIL VIATRIS 50 mg, comprime secable -- medicine extractBase de Donnees Publique des Medicaments (ANSM / French Ministry of Health) -- official French medicines database · European Union (France) · dated 1998-07-06 · accessed 2026-07-31 · source 3
  4. CAPOTEN (captopril) Tablets, USP, 12.5, 25, 50 and 100 mg -- Product MonographHealth Canada -- Product Monograph (Bristol-Myers Squibb Canada) · Canada · dated 2006-11-08 · accessed 2026-07-31 · source 4
  5. CAPOTEN (captopril) 12.5mg/25mg/50mg tablets and 5mg/mL oral liquid -- ARTG registrations 19247/19248/60608/68962Therapeutic Goods Administration (TGA), Australia -- ARTG entries · Australia · dated 1991-09-30 · accessed 2026-07-31 · source 5
  6. CAPOTEN Captopril Oral Solution 5mg/mL -- New Zealand Data SheetMedsafe (New Zealand Medicines and Medical Devices Safety Authority) · New Zealand · dated 2025-01-01 · accessed 2026-07-31 · source 6

Brand names by country

Single-ingredient captopril names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Capoten (captopril) (1)FDA approved confirmed · 12.5 mg, 25 mg, 50 mg, 100 mg · Bristol-Myers Squibb (originator); widely available generic

United Kingdom

  • Captopril (generic; oral solution and tablets) (2)MHRA licensed confirmed · 5 mg/5ml, 25 mg/5ml oral solution; tablet strengths also marketed · Martindale Pharmaceuticals Limited (Martindale Pharma), among others

Canada

  • APO-CAPTO

Australia

  • Capoten (captopril) (5)TGA ARTG registered confirmed 19247 19248 · 12.5 mg, 25 mg, 50 mg, 5 mg/mL oral liquid · Arrotex Pharmaceuticals Pty Ltd

New Zealand

  • Capoten (captopril oral solution) (6)Medsafe listed confirmed · 5 mg/mL · Medsafe-listed sponsor
View brands in additional countries.

European Union

Captopril Viatris / Lopril / Captolane (3)

This page provides general reference information about captopril (Capoten) and is not a substitute for advice from your pharmacist or clinician. If you are pregnant, think you might be pregnant, or are planning a pregnancy, contact your clinician urgently before starting or continuing captopril. Seek emergency medical attention for swelling of the face, lips, tongue, or throat, difficulty breathing, or signs of infection such as fever or sore throat.

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