• you are allergic to any ingredient in Cardizem
• 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 Cardizem. 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 Cardizem. 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 Cardizem
• Rifampin because it may decrease the effectiveness of Cardizem
• 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 Cardizem.

This may not be a complete list of all interactions that may occur. Ask your health care provider if Cardizem 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.

Important safety information:

• Cardizem may cause dizziness. These effects may be worse if you take it with alcohol or certain medicines. Use Cardizem with caution. Do not drive or perform other possible unsafe tasks until you know how you react to it.
• Cardizem 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.
• Cardizem may cause you to become sunburned more easily. Avoid the sun, sunlamps, or tanning booths until you know how you react to Cardizem. 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 Cardizem 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 Cardizem. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
• Use Cardizem with caution in the elderly; they may be more sensitive to its effects.
• Cardizem 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 Cardizem while you are pregnant. Cardizem is found in breast milk. Do not breastfeed while taking Cardizem.

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; symptoms of liver problems (eg, yellowing of the skin or eyes, dark urine, pale stools); tender, bleeding, or swollen gums.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.