Risks associated with flecainide: Therapeutic doses of flecainide range from 200 mg to 300 mg per day. Common side effects of flecainide therapy include dizziness (19% to 30%), visual disturbances (16%), dyspnea (10%), palpitations (6%), chest pain (5%), edema (3.5%), tachycardia (1% to 3%), proarrhythmia (4% to 12%), sinus node dysfunction (1.2%), syncope, headache (4% to 10%), fatigue (8%), nervousness (5%), fever, malaise, hypoesthesia, paresis, ataxia, vertigo, somnolence, tinnitus, anxiety, insomnia, depression, rash (1% to 3%), nausea (9%), constipation (1%), abdominal pain (3%), anorexia (1% to 3%), diarrhea (0.7% to 3%), tremor (5%), weakness (5%), paresthesia (1%), diplopia (1% to 3%), and blurred vision. Rare (< 1%) side effects include alopecia, altered pacing threshold, amnesia, angina, AV block, bradycardia, bronchospasm, heart failure, corneal deposits, depersonalization, euphoria, exfoliative dermatitis, granulocytopenia, heart block, increased PR interval, leukopenia, metallic taste, neuropathy, paradoxical increase in ventricular rate in atrial fibrillation/flutter, paresthesia, photophobia, pneumonitis, pruritus, increased QRS duration, swollen lips/tongue/mouth, tardive dyskinesia, thrombocytopenia, urinary retention, urticaria, and ventricular arrhythmias.