I was on 4 grams of Valtrex for about 1.5 years. I had some improvement but decided to go off after totally relapsing and side effects. The most bothersome side effect was lower back pain (kidneys). I drank almost a gallon of water a day while on valtrex but sometimes it was still bothersome. I was thinking of trying Valtrex or acyclovir again at a lower dose- perhaps 500mg 3x a day. 4 grams was just was too much. I know that is the "therapeutic" dose but I feel it was too much for my body- I'm a small person too. Does anyone one if perhaps acyclovir is easier on the kidneys than Valtrex? I think it just takes an additional step in the body to convert to what valtrex is/does (hope I got that right) Anyone has a dose recommendation for acyclovir? I think EBV is likely still the main culprit. I was on Valcyte also for a year but had to stop it for various reasons. My HHV-6 levels actually dopped down to "negative" I think while on Valcyte. Valcyte also isn't something I can consider trying again at this point. P.S. I tried Famvir- It gave me horrendous muscle pain!! Thanks.