Medically reviewed on March 15, 2017
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 "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 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 "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
It is not known whether this medicine 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 breast-feed while using this medicine.
How should I take diltiazem?
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 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 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 should I avoid while taking diltiazem?
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 an herbal supplement 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: 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;
heart problems--shortness of breath (even with mild exertion), swelling, rapid weight gain;
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 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.
See also: Side effects (in more detail)
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. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide. 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.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2018 Cerner Multum, Inc. Version: 14.01.
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- Drug class: calcium channel blocking agents