Diltiazem (patient information)
Why this medication is prescribed
Diltiazem is used to treat high blood pressure and to control chest pain (angina). Diltiazem is in a class of medications called calcium-channel blockers. It works by relaxing the blood vessels so the heart does not have to pump as hard. It also increases the supply of blood and oxygen to the heart.
How this medication should be used
Diltiazem comes as a tablet and an extended- or dual-release (long-acting) capsule to take by mouth. The tablet is usually taken three or four times a day with or without food. The capsule is usually taken one or two times a day. The extended-release capsule (Cardizem SR, Dilacor XR, Diltia XT) should be taken on an empty stomach, at least 1 hour before or 2 hours after a meal. The extended-release capsule (Tiazac) may be taken with or without food. The dual-release capsule (Cardizem CD) may be taken with food.
Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take diltiazem exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Swallow the capsules whole; do not split, chew, or crush them.
Your doctor will probably start you on a low dose of diltiazem and gradually increase your dose.
If taken regularly, diltiazem controls chest pain, but it does not stop chest pain once it starts. Your doctor may give you a different medication to take when you have chest pain.
Diltiazem controls high blood pressure and chest pain (angina) but does not cure them. It may take up to 2 weeks before you feel the full benefit of diltiazem. Continue to take diltiazem even if you feel well. Do not stop taking diltiazem without talking to your doctor.
Other uses for this medicine
Diltiazem is also used sometimes to treat Raynaud's syndrome. Talk to your doctor about the possible risks of using this drug for your condition.
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
Special Precautions
Before taking diltiazem:
- tell your doctor and pharmacist if you are allergic to diltiazem or any other drugs.
- tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially heart and blood pressure medications such as beta-blockers, digoxin (Lanoxin), quinidine (Quinaglute, Quinidex), and diuretics (water pills); carbamazepine (Tegretol); cimetidine (Tagamet); cyclosporine (Neoral, Sandimmune); fentanyl (Duragesic); medications to treat depression; medications to treat glaucoma (increased pressure in the eye); theophylline; and vitamins.
- tell your doctor if you have or have ever had heart, liver, or kidney disease.
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking diltiazem, call your doctor.
- if you are having surgery, including dental surgery, tell your doctor or dentist that you are taking diltiazem.
Special dietary instructions
Talk to your doctor before using salt substitutes containing potassium. If your doctor prescribes a low-salt or low-sodium diet, follow these directions carefully.
What to do if you forget a dose
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Side Effects
Minor Side Effects
Diltiazem may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- dizziness or lightheadedness
- flushing (feeling of warmth)
- headache
- excessive tiredness
- slower heartbeat
- upset stomach
- loss of appetite
- vomiting
- diarrhea
- constipation
- stomach pain
- dry mouth
- difficulty falling asleep or staying asleep
Severe Side Effects
If you experience any of the following symptoms, call your doctor immediately:
- swelling of the face, eyes, lips, tongue, arms, or legs
- difficulty breathing or swallowing
- fainting
- rash
- yellowing of the skin or eyes
- fever
- increase in frequency or severity of chest pain (angina)
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/MedWatch/report.htm] or by phone [1-800-332-1088].
Storage conditions needed for this medication
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of emergency/overdose
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
Other information
Keep all appointments with your doctor and the laboratory. Your blood pressure should be checked regularly to determine your response to diltiazem.
Your doctor may ask you to check your pulse (heart rate) daily and will tell you how fast it should be. If your pulse is slower than it should be, call your doctor for directions on taking diltiazem that day. Ask your doctor or pharmacist to teach you how to check your pulse.
The extended-release capsule does not dissolve in the stomach after swallowing. It slowly releases the medicine as it passes through your small intestines. It is not unusual to see the capsule shell in your stool.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
Brand names
- Cardizem®
- Cardizem® CD
- Cardizem® Lyo-Ject®
- Cardizem® Monovial®
- Cardizem® SR
- Cartia XT®
- Dilacor XR®
- Diltia XT®
- Tiazac®