Diltiazem

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 · Canada

Australia: · 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 diltiazem hydrochloride is 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.
(1)

How to take diltiazem hydrochloride

  • 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.
(2) (1)

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)

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 testEffectAction
Beta-blockers and digoxinCombined 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 medicinesDiltiazem 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.
(1) (2)

Storage

Store according to the instructions on your product's packaging or pharmacist's label.

Study the drug class: Non-dihydropyridine calcium channel blockers

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)

Mechanism of action

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)

What is the generic name of Diltiazem?

The generic name is diltiazem hydrochloride. It is sold under brand names including Adizem, Angitil, Tildiem, Viazem, Zemtard (United Kingdom). (1) (2)

What class of drug is diltiazem hydrochloride?

Diltiazem is classed as: Non-dihydropyridine calcium channel blocker. (1) (2)

References

  1. DILTIAZEM HYDROCHLORIDE extended-release tablets — prescribing informationDailyMed, U.S. National Library of Medicine (FDA-approved label) · United States · accessed 2026-07-26 · source 1
  2. DiltiazemNHS (United Kingdom) · United Kingdom · accessed 2026-07-26 · source 2
  3. 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
  4. Diltiazem — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
  5. diltiazem hydrochloride — FDA approval record (Drugs@FDA ANDA208783)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
  6. 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 ER120 mg, 300 mg, 180 mg, 420 mg, 360 mg, 240 mg · zydus pharmaceuticals (usa) inc.
  • Cartia XT240 mg, 120 mg, 180 mg, 300 mg · actavis pharma, inc.
  • Cardizem360 mg, 120 mg, 420 mg, 60 mg, 240 mg, 30 mg, 300 mg, 180 mg · bausch health us llc
  • TIAZAC EXTENDED RELEASE360 mg, 120 mg, 300 mg, 420 mg, 180 mg, 240 mg · bausch health us, llc
  • Matzim LA420 mg, 180 mg, 240 mg, 300 mg, 360 mg · actavis pharma, inc.
  • DILTIAZEM HCI100 mg, 5 mg/mL · hf acquisition co llc, dba healthfirst

Canada

  • DILTIAZEM CD
  • TIAZAC
  • TIAZAC XC
  • DILTIAZEM TZ
  • CARDIZEM CD
  • SANDOZ DILTIAZEM T
  • TEVA-DILTIAZEM HCL ER
  • APO-DILTIAZ TZ
  • ACT DILTIAZEM T
  • APO-DILTIAZ CD
View brands in additional countries.

This page provides general medicine information, not a diagnosis, prescription, or substitute for a doctor, pharmacist, or the current local product information.

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