My specialist is considering switching me from Valtrex to Famvir now. Even with a high dose of Valtrex, my EBV keeps reactivating. She says they're seeing Valtrex-resistant HSV and EBV because, as with antibiotics, some people (mostly those with genital herpes and HIV) are not using the antiviral correctly thereby killing off the weaker strains but leaving those more resistant to the meds to propagate throughout the population. It's also possible that Famvir has more activity against other herpesviruses than is known, so it's better at keeping multiple infections suppressed. So, if my EBV tests this week show EBV reactivated again, we'll do the switch to Famvir. If I see any changes in my immune results that suggest it's doing better than the Valtrex for me now, I'll pass on that info.