Cardizem (Diltiazem) - Oral

What Is Cardizem?

Cardizem (diltiazem) is an oral prescription medication used to treat high blood pressure and other heart problems. It is part of the drug class called calcium channel blockers. It widens and relaxes blood vessels in the body and heart, which makes it easier for blood flow. The drug also increases oxygen delivery and makes it easier for the heart to pump blood.

Diltiazem is available as a long-acting capsule (Cardizem CD), regular-release tablets (Cardizem), and long-acting tablets (Cardizem LA). The drug is taken by mouth (oral).

Drug Facts

Generic Name: Diltiazem
Brand Name: Cardizem
Drug Availability: Prescription
Administration Route: Oral
Therapeutic Classification: Calcium channel blocker
Available Generically: Yes
Controlled Substance: No
Active Ingredient: Diltiazem
Dosage Form(s): Long-acting capsules, regular-release tablets, long-acting tablets

What Is Cardizem Used For?

Cardizem (diltiazem) is a prescription drug that is used to treat:

How to Take Cardizem

Take this drug at the same time of day. Here is how to take each form of the medication.

Regular release tablet:

  • Take it before meals and at bedtime.
  • You may swallow, crush, break or chew the regular-release tablets. If your tablets are 30 milligrams (mg), do not break or split the pill. The 30mg tablet does not have a line down the middle (scored).
  • If the tablet is not scored, do not cut it in half.

Long-acting preparations:

  • Take at the same time (morning or night) with or without food.
  • Take it with a full glass of water.
  • Swallow the tablets whole. Do not break, chew or crush the long-acting tablets and 12-hour capsules.

Some long-acting drugs include Cardizem CD, Cardizem LA, Cartia XT, and Matzim LA.


Store your medication in a cool, dry place and avoid moisture. Do not store it in a bathroom. Store diltiazem at room temperature at around 77 degrees Fahrenheit and away from light. The medication can temporarily be stored in cool or mildly hot temperatures (59 to 86 degrees Fahrenheit), such as while you are traveling. Keep diltiazem away from children and pets.

Dispose of any unused and expired medications properly. Do not pour them down the drain, sink, or toilet. Ask your pharmacist about the best way to get rid of your medications. Look out for drug take-back programs in your area.

Off-Label Uses

Cardizem is used off-label to treat:

  • Migraine
  • Irregular heartbeat (atrial fibrillation)
  • Chest pain linked with taking cocaine
  • Abnormally thick heart muscles (hypertrophic cardiomyopathy)
  • Fast and abnormal heart rate (ventricular tachycardia​)
  • Extra heartbeats (ventricular premature beats)
  • High blood pressure in the lungs) (pulmonary hypertension)
  • Abnormally fast and erratic heartbeat (supraventricular tachycardia)

How Long Does Cardizem Take to Work?

Cardizem begins to work within 30 to 60 minutes of taking it. The immediate-release tablets peak within 2 to 4 hours. The extended-release tablets peak within 11 to 18 hours. The extended-release capsules peak in 10 to 14 hours.

What Are the Side Effects of Cardizem? 

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at or 1-800-FDA-1088.

Common Side Effects

There are some possible side effects of Cardizem. Some people taking Cardizem have little to no side effects. If any of these side effects bother you or do not go away, contact your healthcare provider or seek medical help:

These are only some of the possible side effects of this drug. Call your healthcare provider if you have any concerns about side effects.

Severe Side Effects

If you have any severe side effects, tell your provider right away. Call 911 if you have a medical emergency or if your symptoms feel life-threatening. Serious adverse effects of Cardizem include:

  • Signs of an allergic reaction
  • Hives
  • Wheezing
  • Tightness in the chest or throat
  • Trouble breathing, swallowing, or talking
  • Unusual hoarseness
  • Signs of liver problems
  • Dark urine
  • Feeling tired
  • Stomach pain
  • Light-colored stools
  • Yellow skin or eyes
  • Symptoms of heart failure (new or worsening) 
  • Swelling in legs or arms
  • Shortness of breath
  • Big weight gain
  • Severe dizziness or passing out
  • Slow heartbeat
  • Abnormal heartbeat (new or worsening)

Stevens-Johnson syndrome is a severe allergic skin reaction that may occur with diltiazem. It can cause serious health complications that may or may not go away. They can also lead to death. Call your provider right away if you have any of these symptoms while you are taking diltiazem:

  • Irritated or red eyes
  • Sores in your mouth, throat, nose, or eyes
  • Swollen, blistered, red, or peeling skin (with or without fever)

Report Side Effects

Cardizem may cause other side effects. Call your healthcare provider if you have any problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (1-800-332-1088).

Dosage: How Much of Cardizem Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For chest pain:
    • For oral dosage form (extended-release capsules):
      • Adults—At first, 120 milligrams (mg) once a day in the morning. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (extended-release tablets):
      • Adults—At first, 180 milligrams (mg) once a day, either in the morning or evening. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults—At first, 30 milligrams (mg) 4 times a day before meals and at bedtime. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
  • For high blood pressure:
    • For oral dosage form (extended-release capsules):
      • Adults—At first, 180 to 240 milligrams (mg) once a day in the morning. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (extended-release tablets):
      • Adults—At first, 180 to 240 milligrams (mg) once a day, either in the morning or at bedtime. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.


The following changes (modifications) should be kept in mind when using Cardizem:

Severe allergic reaction: Avoid using Cardizem if you have a known allergy to it or any of its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your usual dosing schedule. Do not double the amount or take extra doses to make up for a missed dose.

Overdose: What Happens If I Use Too Much Cardizem? 

Cardizem overdose symptoms may include low blood pressure, low heart rate, heart block, or heart failure.

Call your provider or the Poison Control Center right away if you or someone else may have taken too much Cardizem. 

If someone collapses or is not breathing after taking diltiazem, call 911 immediately.

What Happens If I Overdose on Cardizem?

If you think you or someone else may have overdosed on Cardizem, call a healthcare provider or the Poison Control Center (1-800-222-1222).

If someone collapses or isn't breathing after taking Cardizem, call 911 immediately.


Drug Content Provided by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Dizziness, lightheadedness, or fainting may occur, especially when you get up suddenly from a lying or sitting position If you feel dizzy, lie down so you do not faint. Then sit for a few moments before standing to prevent the dizziness from returning. If you faint, call your doctor right away. .

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Serious skin reactions (eg, Stevens-Johnson syndrome, toxic epidermal necrolysis) can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, chills, cough, diarrhea, itching, joint or muscle pain, red irritated eyes, red skin lesions, often with a purple center, skin rash, sore throat, sores, ulcers, or white spots in the mouth or on the lips, or unusual tiredness or weakness.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn't Take Cardizem? 

Do not take Cardizem if you have:

  • Heart failure
  • Heart attack
  • An allergy to the drug or its ingredients
  • Been prescribed a beta-blocker (like metoprolol)
  • Fluid in your lungs (pulmonary edema)
  • Low blood pressure less than 90 mm Hg systolic (hypotension)
  • Sick sinus syndrome or heart block (except if you have a functioning pacemaker)

What Other Medications Interact With Cardizem?

Using certain drugs while on Cardizem may cause severe reactions. Do not take diltiazem with:

What Medications Are Similar?

Medications similar to Cardizem that can be used to treat high blood pressure and other heart problems are:

Verapamil, like diltiazem, is a calcium channel blocker that can cause similar side effects. However, nebivolol and losartan are in different drug classes. Nebivolol is a beta-blocker, while losartan is an angiotensin II receptor blocker.

All of these medications are safe and effective, but some work better than others, depending on the case. 

For example, losartan works better than diltiazem to reduce protein in the urine in people with kidney disease. Diltiazem is also more effective than nebivolol in treating people with high blood pressure and angina.

This list includes drugs for high blood pressure and other heart conditions. It is NOT a list of medicines recommended to take with Cardizem. Do not take these drugs together unless your healthcare provider tells you to. If you have any problems, talk to your healthcare provider.

Frequently Asked Questions

  • What is Cardizem used to treat?

    Cardizem is used to treat high blood pressure and other heart problems.

  • What should I do if I miss a dose of Cardizem?

    Take the missed dose as soon as you remember. Skip the missed dose if it is close to when you will take your next dose. Return to your regular dosing schedule. Do not take extra doses or double the amount.

  • How soon does Cardizem begin to work?

    Cardizem begins to work within 30 to 60 minutes of taking it. The immediate-release tablets peak in 2 to 4 hours, the extended-release tablets peak in 11 to 18 hours, and the extended-release capsules peak in 10 to 14 hours.

  • What are the common side effects of Cardizem?

    Common side effects of Cardizem are:

    • Feeling dizzy
    • Headache
    • Feeling tired or weak

How Can I Stay Healthy While Taking Cardizem?

High blood pressure is a manageable health condition. I left uncontrolled, it may lead to many health complications. To make sure that your blood pressure is always under control:

  • Take your medications correctly and routinely.
  • Avoid processed and salty foods.
  • Check your blood pressure daily.
  • Keep a blood pressure diary.
  • Avoid drugs that may increase your blood pressure, like ibuprofen and naproxen.
  • Always talk to your healthcare provider before your start, adjust or stop any medicine you take.
  • Consider asking your provider to refer you to a registered dietitian nutritionist to help you with your diet and exercise routine.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Cardizem label.

  2. National Library of Medicine. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012.

  3. Richards JR, Laurin EG. Cocaine. In: StatPearls. StatPearls Publishing; 2021.

  4. Talreja O, Cassagnol M. Diltiazem. In: StatPearls. StatPearls Publishing; 2021.

  5. Salahuddin, Azam MN, Raja KM, et al. The Comparison Of Efficacy Between Losartan And Diltiazem As Antiproteinuric Agent In Non-Diabetic Renal Diseases. J Ayub Med Coll Abbottabad. 2021;33(3):492-495.

  6. Kook H, Hong SJ, Yang KS, et al. Comparison of nebivolol versus diltiazem in improving coronary artery spasm and quality of life in patients with hypertension and vasospastic angina: A prospective, randomized, double-blind pilot study. PLoS One. 2020;15(9):e0239039. Published 2020 Sep 11. doi:10.1371/journal.pone.0239039

By Queen Buyalos, PharmD
Queen Buyalos is a pharmacist and freelance medical writer. She takes pride in advocating for cancer prevention, overall health, and mental health education. Queen enjoys counseling and educating patients about drug therapy and translating complex ideas into simple language.