Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Both propafenone and Class IA and III antiarrhythmics can affect your heart's rhythm. Quinidine may slow down how quickly your liver processes propafenone.
What might happen:
Taking propafenone with other antiarrhythmics can affect your heart rhythm and may increase your risk of an irregular heartbeat, which may be life-threatening. If the other antiarrhythmic is quinidine, the amount of propafenone in your blood may increase.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know right away that you are taking these medicines together. Your doctor may want to check the rhythm of your heart or the amount of propafenone in your blood. Let your doctor know right away if you notice an irregular heartbeat or have any dizziness or fainting episodes.Your healthcare professionals 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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