Treating supraventricular tachycardia, a rhythm disturbance of the heart. It is also used for controlling heart rate response to other rhythm disturbances, specifically, atrial fibrillation and flutter. It may also be used for other conditions as determined by your doctor.

Diltiazem is a calcium channel blocker. It works by slowing the electrical conduction in the heart, slowing heart rate, and/or normalizing heart rhythm.

• you are allergic to any ingredient in Diltiazem
• you have sick sinus syndrome or have second- or third-degree heart block and do not have a pacemaker, or very low blood pressure
• you have atrial fibrillation or flutter and a pre-excitation syndrome (extra conduction pathway in the heart), such as Wolff-Parkinson-White syndrome (WPW) or Lown-Ganong-Levine syndrome (LGL)
• you are receiving injectable beta-blockers (eg, metoprolol) or erythromycin

Contact your doctor or health care provider right away if any of these apply to you.

Some medical conditions may interact with Diltiazem. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
• if you have allergies to medicines, foods, or other substances
• if you have heart failure or have had a recent heart attack with lung congestion, heart block, low blood pressure, a very slow heart rate, or abnormal heart rhythm
• if you have kidney or liver disease

Some MEDICINES MAY INTERACT with Diltiazem. Tell your health care provider if you are taking any other medicines, especially any of the following:

• Cimetidine or protease inhibitors (eg, indinavir) because they may increase the actions and side effects of Diltiazem
• Rifampin because it may decrease the effectiveness of Diltiazem
• Amiodarone, cisapride, digoxin, erythromycin, protease inhibitors (eg, indinavir), quinidine, tricyclic antidepressants (eg, desipramine), theophylline, or general anesthetics because toxic effects on the heart may occur
• Benzodiazepines (eg, midazolam), beta-blockers (eg, metoprolol), buspirone, carbamazepine, cilostazol, corticosteroids (eg, prednisone), cyclosporine, HMG-CoA reductase inhibitors (eg, atorvastatin), macrolide immunomodulators (eg, tacrolimus) because the risk of their side effects, some potentially life-threatening, may be increased by Diltiazem

This may not be a complete list of all interactions that may occur. Ask your health care provider if Diltiazem may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

Use Diltiazem as directed by your doctor. Check the label on the medicine for exact dosing instructions.

• Diltiazem is usually given as an injection at your doctors office, hospital, or clinic. If you will be using Diltiazem at home, a health care provider will teach you how to use it. Be sure you understand how to use Diltiazem. Follow the procedures you are taught when you use a dose. Contact your health care provider if you have any questions.
• Do not use Diltiazem if it contains particles, is cloudy or discolored, or if the vial is cracked or damaged.
• Keep this product, as well as syringes and needles, out of the reach of children and pets. Do not reuse needles, syringes, or other materials. Ask your health care provider how to dispose of these materials after use. Follow all local rules for disposal.
• If you miss a dose of Diltiazem , use it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not use 2 doses at once.

Ask your health care provider any questions you may have about how to use Diltiazem.

• Diltiazem may cause dizziness. These effects may be worse if you take it with alcohol or certain medicines. Use Diltiazem with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
• Diltiazem may cause dizziness, lightheadedness, or fainting; alcohol, hot weather, exercise, or fever may increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects.
• Diltiazem may cause you to become sunburned more easily. Avoid the sun, sunlamps, or tanning booths until you know how you react to Diltiazem. Use a sunscreen or wear protective clothing if you must be outside for more than a short time.
• Tell your doctor or dentist that you take Diltiazem before you receive any medical or dental care, emergency care, or surgery.
• Lab tests, including electrocardiogram (ECG), heart rate, and blood pressure monitoring, may be performed while you use Diltiazem. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
• Use Diltiazem with caution in the ELDERLY; they may be more sensitive to its effects.
• Diltiazem should not be used in CHILDREN; safety and effectiveness in children have not been confirmed.
• PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Diltiazem while you are pregnant. Diltiazem is found in breast milk. Do not breast-feed while taking Diltiazem.

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Constipation; dizziness; facial flushing; headache; weakness.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); hallucinations; irregular heartbeat; swelling of the feet or hands; tender, bleeding, or swollen gums.