Diltiazem
Diltiazem is a calcium channel blocker that relaxes blood vessels and can slow the heart rate, used to lower blood pressure and reduce chest pain (angina) related to coronary heart disease. Diltiazem is used for Hypertension, Chronic stable angina and High blood pressure, angina, and coronary heart disease.
Also called: Cardizem (United States) · Tildiem (United Kingdom) · Tiazac (Canada) · Vasocardol Cd (Australia) · Angiozem (Philippines)
Pronunciation: pronunciation varies by local usage.
- Generic name
- diltiazem hydrochloride
- Brand names
- Adizem, Angitil, Tildiem, Viazem, Zemtard (United Kingdom)
- Drug class
- Non-dihydropyridine calcium channel blocker
- Form
- Standard-release or slow/extended-release tablet or capsule, depending on the exact product; a separate topical cream product exists for anal fissure and is not covered by this page.
- Route
- Oral
- Legal status
- Prescription-only medicine
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · India · Nepal · New Zealand
Australia: Cardizem CD, Cardizem, Vasocardol CD, Diltiazem Sandoz CD, Vasocardol · Full directory
What diltiazem hydrochloride is and how it works
Diltiazem is a calcium channel blocker that relaxes blood vessels and can slow the heart rate, used to lower blood pressure and reduce chest pain (angina) related to coronary heart disease. (1) (2)
The exact indication, dose, and formulation (standard-release or slow-release) are individualised by the prescriber. Do not confuse the oral heart/blood-pressure product with a separate topical diltiazem cream sometimes used for anal fissure.
Mechanism of action: how diltiazem hydrochloride works
Diltiazem is a non-dihydropyridine calcium channel blocker that relaxes vascular smooth muscle (reducing peripheral resistance and blood pressure) and reduces myocardial oxygen demand; it inhibits the CYP3A4 enzyme. (1)
What is Diltiazem hydrochloride used for?
Hypertension (United States)
Extended-release diltiazem is indicated for the treatment of hypertension, to lower blood pressure, alone or with other antihypertensive medicines. (1)
Chronic stable angina (United States)
Indicated to improve exercise tolerance in patients with chronic stable angina, by reducing myocardial oxygen demand. (1)
High blood pressure, angina, and coronary heart disease (United Kingdom)
Used in the UK for high blood pressure, angina, and coronary heart disease, at a dose and schedule set by the prescriber based on the reason for treatment. (2)
Before taking diltiazem hydrochloride
Do not take / not appropriate for
- Do not take diltiazem if you have sick sinus syndrome or second- or third-degree heart block, unless you have a working pacemaker. (United States extended-release label) (1)
- Do not take diltiazem if your systolic blood pressure is below 90 mmHg, if you have had a recent heart attack with fluid in the lungs, or if you have a known hypersensitivity to diltiazem. (United States extended-release label) (1)
Tell your clinician about
- Any heart-rhythm problem, slow heartbeat, or heart failure.
- Liver disease.
- Every other medicine, especially beta-blockers, digoxin, statins (particularly simvastatin), benzodiazepines, and ciclosporin.
- Pregnancy, plans for pregnancy, or breastfeeding.
Diltiazem hydrochloride dosage and how to take it
- Take exactly as prescribed for your specific condition and product.
- Swallow tablets or capsules whole with water; do not chew or crush them.
- Can be taken with or without food; take at the same time(s) each day.
- Do not stop taking diltiazem or change your other medicines without talking to your prescriber first.
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)
Missed dose
Follow the missed-dose rule for your exact schedule: if taken once daily, take the missed dose as soon as you remember unless it is less than 12 hours until the next dose, in which case skip it; if taken twice daily, skip if less than 4 hours remain until the next dose; if taken three times daily, skip the missed dose. Never take an extra dose to make up for a missed one; ask your pharmacist or prescriber if you are unsure.
Overdose
If you have taken more than your prescribed dose, contact your prescriber or a poison-control/urgent-advice service for guidance. Seek emergency care immediately if you have fainting, severe dizziness, a very slow or irregular heartbeat, or severe drowsiness; call emergency services rather than driving yourself. (2)
Diltiazem hydrochloride side effects
Effects differ somewhat depending on whether diltiazem is used for blood pressure or angina.
Swelling of the lower legs or ankles
What to notice: Reported commonly in both hypertension and angina treatment.
What to do: Tell your prescriber if swelling is severe or bothersome. (1)
Headache, dizziness, or fatigue
What to notice: Reported particularly in patients treated for angina.
What to do: Tell your prescriber if severe or persistent. (1)
Possible liver problem
What to notice: Signs of a possible liver problem.
What to do: Contact your prescriber promptly; a clinician will decide whether diltiazem needs to be stopped and whether liver-function testing is needed. (1)
Slow or irregular heartbeat
What to notice: Marked slowing of the pulse, dizziness, or fainting.
What to do: Contact your prescriber promptly; this may need dose review, especially if you also take a beta-blocker or digoxin. (1)
Serious warnings
Severe skin reaction — emergency
Symptoms: Signs of a severe skin reaction, which can indicate Stevens-Johnson syndrome, toxic epidermal necrolysis, or erythema multiforme.
Action: Seek emergency medical help immediately; a clinician or emergency service will decide whether diltiazem needs to be stopped. (1)
Worsening heart failure — urgent
Symptoms: Increasing breathlessness, swelling, or fatigue, particularly in people with existing reduced heart pumping function.
Action: Contact your prescriber urgently; this risk is higher when diltiazem is combined with a beta-blocker. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Beta-blockers and digoxin | Combined use increases the risk of a very slow heartbeat, conduction problems, or worsening heart failure. | The prescriber will monitor heart rate and rhythm closely if these are combined. (1) |
| Simvastatin and other CYP3A4-metabolised medicines | Diltiazem inhibits the CYP3A4 enzyme and can increase blood levels of medicines processed by it, including simvastatin, some benzodiazepines, and ciclosporin. | The prescriber or pharmacist should review your complete medicine list; a dose adjustment may be needed. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Liver impairment
Mild to moderate liver impairment usually needs no dose change, but severe liver impairment can increase diltiazem levels; discuss any liver disease with your prescriber. (1)
Kidney impairment
No renal dose adjustment is needed based on the reviewed label, but tell your prescriber about any kidney disease. (1)
Pregnancy and breastfeeding
The product label includes pregnancy and breastfeeding guidance. Discuss the balance of benefits and risks with your prescriber before taking diltiazem in pregnancy or while breastfeeding. (1)
Monitoring
Before starting
- Confirm the indication, exact product, and whether it is standard-release or slow-release.
- Review heart rhythm, blood pressure, heart failure history, liver disease history, and all current medicines, especially beta-blockers and digoxin.
During treatment
- Monitor blood pressure and heart rate/rhythm as clinically indicated.
- Watch for signs of liver problems.
- Do not stop or change the dose, or start/stop another medicine, without checking with your prescriber.
Storage
Store according to the instructions on your product's packaging or pharmacist's label.
Study the drug class: Non-dihydropyridine calcium channel blockers (practice MCQs)
Professional information
Clinician-facing context only. Use the current local product information for exact dosing and titration.
United States
Indication: Hypertension
Dose summary: Extended-release: initial 180-240 mg once daily, titrated according to blood pressure response, up to a maximum of 540 mg/day.
Renal context: No renal dose adjustment is described. Hepatic impairment: no adjustment needed for mild-to-moderate impairment; severe impairment increases drug levels and bioavailability. (1)
United States
Indication: Chronic stable angina
Dose summary: Extended-release: initial 180 mg once daily, titrated per response.
Renal context: As above. (1)
Hepatic guidance
Increased drug levels and bioavailability occur in severe hepatic impairment; use local product information and clinical judgement.
Overdose note
Overdose requires urgent clinical assessment; manage per local emergency and toxicology guidance. (1)
Frequently asked questions
What is diltiazem hydrochloride used for?
diltiazem hydrochloride is prescribed for approved indications. Always follow your healthcare provider's guidance.
What are the side effects of diltiazem hydrochloride?
Common side effects may include gastrointestinal symptoms and headache. Serious side effects require immediate medical attention.
Can I take diltiazem hydrochloride with other medications?
Always inform your healthcare provider about all medications you are taking, including over-the-counter products and supplements.
What is the mechanism of action of diltiazem hydrochloride?
Diltiazem is a non-dihydropyridine calcium channel blocker that relaxes vascular smooth muscle (reducing peripheral resistance and blood pressure) and reduces myocardial oxygen demand; it inhibits the CYP3A4 enzyme. (1)
References
- DILTIAZEM HYDROCHLORIDE extended-release tablets — prescribing informationDailyMed, U.S. National Library of Medicine (FDA-approved label) · United States · accessed 2026-07-26 · source 1
- DiltiazemNHS (United Kingdom) · United Kingdom · accessed 2026-07-26 · source 2
- TIAZAC EXTENDED RELEASE (DILTIAZEM HYDROCHLORIDE) CAPSULE, EXTENDED RELEASE [BAUSCH HEALTH US, LLC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Diltiazem — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- diltiazem hydrochloride — FDA approval record (Drugs@FDA ANDA208783)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- diltiazem — RxNorm normalized drug concept (RXCUI 203211)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient diltiazem hydrochloride names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- TIADYLT ERcapsule, extended release · 120 mg, 300 mg, 180 mg, 420 mg, 360 mg, 240 mg · zydus pharmaceuticals (usa) inc.regulator source
- Cartia XTcapsule, extended release · 240 mg, 120 mg, 180 mg, 300 mg · actavis pharma, inc.regulator source
- Cardizemcapsule, coated, extended release, tablet, extended release, tablet, coated · 360 mg, 120 mg, 420 mg, 60 mg, 240 mg, 30 mg, 300 mg, 180 mg · bausch health us llcregulator source
- TIAZAC EXTENDED RELEASEcapsule, extended release · 360 mg, 120 mg, 300 mg, 420 mg, 180 mg, 240 mg · bausch health us, llcregulator source
- Matzim LAtablet, extended release · 420 mg, 180 mg, 240 mg, 300 mg, 360 mg · actavis pharma, inc.regulator source
- DILTIAZEM HCIinjection, powder, lyophilized, for solution, injection · 100 mg, 5 mg/mL · hf acquisition co llc, dba healthfirstregulator source
United Kingdom
- Adizem-SRreference source
- Tildiemreference source
- Angitilreference source
- Viazem XLreference source
- Slozemreference source
- Zemtardreference source
- Dilzemreference source
- Dilcardiareference source
Canada
- DILTIAZEM CDregulator source
- TIAZACregulator source
- TIAZAC XCregulator source
- DILTIAZEM TZregulator source
- CARDIZEM CDregulator source
- SANDOZ DILTIAZEM Tregulator source
- TEVA-DILTIAZEM HCL ERregulator source
- APO-DILTIAZ TZregulator source
- ACT DILTIAZEM Tregulator source
- APO-DILTIAZ CDregulator source
Australia
- Cardizem CDreference source
- Cardizemreference source
- Vasocardol CDreference source
- Diltiazem Sandoz CDreference source
- Vasocardolreference source
India
Source-listed products; local stock and regulatory approval have not been confirmed. Check the exact ingredient, strength, and formulation with a pharmacist.
- Diltanol 90mg Tablet SRTablet SR · 90mg · Knoll Pharmaceuticals Ltdpharmacy source · checked 2026-09-24
- Dilzem CD 90 Capsule ERCapsule ER · 90mg · Torrent Pharmaceuticals Ltdpharmacy source · checked 2026-09-24
- Dilzem 30 Tablet CRTablet CR · 30mg · Torrent Pharmaceuticals Ltdpharmacy source · checked 2026-09-24
- Angizem CD 90 Capsule ERCapsule ER · 90mg · Sun Pharmaceutical Industries Ltdpharmacy source · checked 2026-09-24
- Dilcontin XL 90 TabletTablet CR · 90mg · Modi Mundi Pharma Pvt Ltdpharmacy source · checked 2026-09-24
- Angizem 30 Tablet MRTablet MR · 30mg · Sun Pharmaceutical Industries Ltdpharmacy source · checked 2026-09-24
- Channel 90mg Tablet PRTablet PR · 90mg · Micro Labs Ltdpharmacy source · checked 2026-09-24
- DilOK 60 TabletTablet · 60mg · Zeelab Pharmacy Pvt Ltdpharmacy source · checked 2026-09-24
Nepal
Source-listed products; local stock and regulatory approval have not been confirmed. Check the exact ingredient, strength, and formulation with a pharmacist.
- AngizemTablet · 30mg · Sun Pharmaceutical Industries Ltd.reference source · checked 2026-09-24
- AnigizemTablet · 30gm · Sun Pharmaceutical Industries Ltd.reference source · checked 2026-09-24
- DilcontinTablet · 60mg · Modi Mundi Pharma Pvt Ltd.reference source · checked 2026-09-24
- DilgardTablet · 30gm · Cipla Ltd.reference source · checked 2026-09-24
- DiltimeTablet · 90mg · Zydus Pharmaceuticalsreference source · checked 2026-09-24
- DilzemTablet · 30gm · Torrent Pharmaceuticals Ltd.reference source · checked 2026-09-24
New Zealand
- Cardizem CDreference source
- Diltiazem CD Clinectreference source
View brands in additional countries.
Philippines
Angiozem