How the interaction occurs:
When verapamil and quinidine are taken together, your body may not process quinidine properly and your blood levels of quinidine may increase. When nifedipine and quinidine are taken together, your body may not process quinidine properly and your blood levels of quinidine may increase or decrease. Quinidine may cause your body to process nifedipine more slowly and increase your blood levels of nifedipine.
What might happen:
If you are taking verapamil and quinidine, you may experience a decrease in blood pressure. If you are taking nifedipine and quinidine, you may experience an increase or decrease in the effects of quinidine on your heart and an increase in the effects of nifedipine. If nifedipine is stopped, you may experience a decrease in your blood levels of quinidine.
What you should do about this interaction:
If you are taking verapamil and quinidine and you experience weakness, fatigue, or dizziness, contact your doctor. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose of one or both of your medicines.If you are taking nifedipine and quinidine and you notice a fast or irregular heartbeat, contact your doctor. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose of one or both of your medicines. If your doctor stops your nifedipine and you experience nausea, vomiting, stomach pain, drowsiness, trouble breathing, ringing in the ears, vision problems, dizziness, or headache, contact your doctor.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
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