In addition to adverse cardiovascular effects of flecainide, other adverse effects include:

• CNS—headache, drowsiness, dizziness, syncope, fatigue, blurred vision, tremor, ataxia, vertigo, light-headedness, paresthesia, flushing
• Respiratory—dyspnea
• GI—nausea, vomiting, constipation, abdominal pain, diarrhea, anorexia
• Hematologic—neutropenia.