Generic Name: diltiazem (dil TYE a zem)
Brand Name: Cardizem (and Cardizem CD, LA and XR), Cartia XT, Dilacor XR, Dilt-CD, Diltia XT, Dilt-XR, Diltzac, Matzim LA, Taztia XT, Tiadylt ER, Tiazac
Medically reviewed by Kaci Durbin, MD. Last updated on April 1, 2021.
What is diltiazem?
Diltiazem is a calcium channel blocker. It works by relaxing the muscles of your heart and blood vessels.
Diltiazem may also be used for purposes not listed in this medication guide.
You should not use diltiazem if you have very low blood pressure, a serious heart condition such as "sick sinus syndrome" or "second- or third-degree AV block" (unless you have a pacemaker), or if you have recently had a heart attack and you have a build-up of fluid in your lungs.
Before taking diltiazem, tell your doctor if you have kidney disease, liver disease, or congestive heart failure.
Diltiazem may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Do not stop taking this medication without first talking to your doctor. If you stop taking diltiazem suddenly, your condition may become worse.
Diltiazem may be only part of a complete program of treatment that also includes diet, exercise, and other medications. Follow your diet, medication, and exercise routines very closely.
If you are being treated for high blood pressure, keep using this medicine even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life. However, if you have symptoms of low blood pressure (dizziness, fainting, weakness, or blurred vision), call your doctor and stop taking diltiazem.
Before taking this medicine
You should not use diltiazem if you are allergic to it, or if you have:
a serious heart condition such as "sick sinus syndrome" or "second- or third-degree AV block" (unless you have a pacemaker);
very low blood pressure; or
if you have recently had a heart attack and you have a build-up of fluid in your lungs.
To make sure diltiazem is safe for you, tell your doctor if you have:
congestive heart failure; or
if you also take digoxin, or a beta blocker (such as atenolol, carvedilol, metoprolol, propranolol, sotalol, and others).
It is not known whether diltiazem will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.
Diltiazem can pass into breast milk and may harm a nursing baby. You should not breastfeed while using this medicine.
How should I take diltiazem?
Take diltiazem exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose. Do not use this medicine in larger or smaller amounts or for longer than recommended.
Do not crush, chew, break, or open an extended-release diltiazem tablet or capsule. Swallow it whole.
To make swallowing easier, ask your doctor or pharmacist if you can open a diltiazem capsule and sprinkle the medicine into a spoonful of applesauce. Swallow right away without chewing. Do not save the mixture for later use.
Use diltiazem regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.
You should not stop using diltiazem suddenly. Stopping suddenly may make your condition worse.
If you are being treated for high blood pressure, keep using this medicine even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life.
Your blood pressure will need to be checked often. You may also need frequent blood tests.
Store diltiazem at room temperature away from moisture and heat.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of diltiazem can be fatal.
Overdose symptoms may include slow heartbeat, weakness, chest pain, shortness of breath, or fainting.
What to avoid
Grapefruit and grapefruit juice may interact with diltiazem and lead to unwanted side effects. Discuss the use of grapefruit products with your doctor.
Diltiazem may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.
Avoid drinking alcohol while taking diltiazem.
Avoid taking herbal supplements containing St. John's wort at the same time you are taking diltiazem.
Diltiazem side effects
Get emergency medical help if you have signs of an allergic reaction to diltiazem: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
pounding heartbeats or fluttering in your chest;
a light-headed feeling, like you might pass out;
shortness of breath (even with mild activity), swelling, rapid weight gain;
nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
severe skin reaction - fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Common diltiazem side effects may include:
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect diltiazem?
Many drugs can interact with diltiazem, and your doctor may need to change your treatment plan if you use certain other medicines. The following are common drugs that interact with diltiazem;
- Medications used in anesthesia;
- Anti-anxiety medications called benzodiazepines (such as midazolam, triazolam, and others) as well as busipirone;
- Beta-blockers (such as atenolol, carvedilol, metoprolol, propranolol, sotalol, and others);
- Rifampin; and
- Cholesterol medication called statins (such as atorvastatin, lovastatin, simvastatin, rosuvastatin, and others)
Not all possible interactions are listed in this medication guide.
Other prescription and over-the-counter medicines, vitamins, and herbal products may interact with diltiazem. Tell your doctor about all medicines you use, and those you start or stop using. Give a list of all your medicines to any healthcare provider who treats you.
More about diltiazem
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Compare Alternatives
- Support Group
- Pricing & Coupons
- En Español
- 143 Reviews
- Drug class: calcium channel blocking agents
Related treatment guides
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use diltiazem only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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