Diltiazem Tablets

Diltiazem is a calcium channel blocker that treats high blood pressure and angina (chest pain). It makes your heart’s workload easier. You may need to take diltiazem more than once a day. Follow your healthcare provider’s instructions for taking it. They may increase your dose little by little.


What is this medication?

DILTIAZEM (dil TYE a zem) treats high blood pressure and prevents chest pain (angina). It works by relaxing the blood vessels, which helps decrease the amount of work your heart has to do. It belongs to a group of medications called calcium channel blockers.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.



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What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

  • Heart attack
  • Heart disease
  • Irregular heartbeat or rhythm
  • Low blood pressure
  • An unusual or allergic reaction to diltiazem, other medications, foods, dyes, or preservatives
  • Pregnant or trying to get pregnant
  • Breast-feeding

How should I use this medication?

Take this medication by mouth. Take it as directed on the prescription label at the same time every day. Keep taking it unless your care team tells you to stop.

Talk to your care team about the use of this medication in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.


What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medication?

Do not take this medication with any of the following:

  • Cisapride
  • Hawthorn
  • Pimozide
  • Ranolazine
  • Red yeast rice

This medication may also interact with the following:

  • Buspirone
  • Carbamazepine
  • Cimetidine
  • Cyclosporine
  • Digoxin
  • Local anesthetics or general anesthetics
  • Lovastatin
  • Medications for anxiety or difficulty sleeping like midazolam and triazolam
  • Medications for high blood pressure or heart problems
  • Quinidine
  • Rifampin, rifabutin, or rifapentine

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.


What should I watch for while using this medication?

Visit your care team for regular checks on your progress. Check your blood pressure as directed. Ask your care team what your blood pressure should be. Also, find out when you should contact them.

Do not treat yourself for coughs, colds, or pain while you are using this medication without asking your care team for advice. Some medications may increase your blood pressure.

This medication may cause serious skin reactions. They can happen weeks to months after starting the medication. Contact your care team right away if you notice fevers or flu-like symptoms with a rash. The rash may be red or purple and then turn into blisters or peeling of the skin. Or, you might notice a red rash with swelling of the face, lips or lymph nodes in your neck or under your arms.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medication affects you. Do not stand up or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Heart failure—shortness of breath, swelling of the ankles, feet, or hands, sudden weight gain, unusual weakness or fatigue
  • Slow heart beat—dizziness, feeling faint or lightheaded, trouble breathing, unusual weakness or fatigue
  • Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
  • Low blood pressure—dizziness, feeling faint or lightheaded, blurry vision
  • Redness, blistering, peeling, or loosening of the skin, including inside the mouth

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

  • Constipation
  • Facial flushing, redness
  • Headache

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children and pets.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from moisture. Keep the container tightly closed. Throw away any unused medication after the expiration date.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

Additional Common Questions

What does diltiazem do to the heart rate?

The heart has natural pacemaker cells that depend on the passage of calcium to set a heart rate. Diltiazem lowers your heart rate by slowing the flow of calcium across these pacemaker cells of the heart.

Why take diltiazem on an empty stomach?

Taking long-acting diltiazem on an empty stomach keeps your body from absorbing the medicine too quickly. If you take it with high-fat foods, your body may absorb the drug faster.

Does diltiazem lower blood pressure?

Yes. It dilates or opens your blood vessels more, which brings down your blood pressure.

Does diltiazem cause weight gain?

In general, no. However, for some people, diltiazem can cause swelling (edema) in your hands, feet or ankles, and this fluid weight can make you weigh more.

A note from Cleveland Clinic

Sometimes, changing your eating and exercise habits isn’t enough to bring down your blood pressure numbers. For many people, that means adding a blood pressure medicine to their routine. You’re not alone in this. Don’t hesitate to ask your healthcare provider any questions you have about the medicine you’re taking. They’ll want to make sure you have the information you need.

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Note: Introduction and Additional Common Questions written and medically approved by Cleveland Clinic professionals.

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