Hi Paige,
This is a great question. I do work with fresh lemon balm tincture internally as well as oil of fresh lemon balm externally for both HSV and shingles outbreaks. It works very well alongside St. John’s Wort (internally-if safe and externally).
For prevention, it depends on the person and if they know when they may be likely to get a flare (e.g. stressful times, sickness etc.) and they could work with both lemon balm and St. John’s wort preventative (internally and externally) during that time. The dose needs to be sufficient and the preparations must be made from fresh plant.
With warmth,
Benna