Propafenone, sold under the brand name Rythmol among others, is a class 1c anti-arrhythmic medication, which is used to treat illnesses associated with rapid heart beat such as atrial and ventricular arrhythmias.

Propafenone differs from the prototypical class Ic antiarrhythmic in that it has additional activity as a beta-adrenergic blocker which can cause bradycardia and bronchospasm.

Side effects attributed to propafenone include hypersensitivity reactions, lupus-like syndrome, agranulocytosis, CNS disturbances such as dizziness, lightheadedness, gastrointestinal upset, a metallic taste and bronchospasm.

No consensus exists regarding the safety of this practice, and information is needed to determine which agents and which patients are appropriate for outpatient initiation of antiarrhythmic therapy.

[2] Caution should be used in administering propafenone in individuals with hepatic dysfunction, asthma, congestive heart failure, or bradycardia.