Erythema Multiforme Minor (HSV-Associated)

A 26-year-old woman presents with recurrent crops of typical target lesions on the dorsal hands and elbows, appearing 10 days after each episode of herpes labialis. She has had 8 episodes in the past 18 months, each causing significant distress and functional impairment. Mucosal involvement is limited to a few oral aphthae. Histology confirms interface dermatitis with apoptotic keratinocytes. The diagnosis is erythema multiforme minor with HSV-1 as the identified trigger. Which of the following management options, marked **B** in the diagram, is the cornerstone of long-term prophylaxis for this patient's recurrent disease?