Hello all. I started on Valtrex about 2 weeks ago, as recommended by my CFS doctor. I noticed that in that time, my general functioning has on average gone from about 50% to maybe 30% on average. Prior to going on the Valtrex, I was having more bad days at 20-30%, which is why I was told to go on the Valtrex, However, on average I was still around 50% and sometimes up to 60%. In the first week of taking the medication, I had severe IBS symptoms. I was kept up at night by them. In addition, I have had many days where I am mostly bedridden, or I don't get out of bed until 5pm. This is not typical for me as I usually can operate at about 50-60%. Is it normal to have a "die off" or Herxheimer reaction to taking anti-viral medications? The only other thing I can imagine making things worse is that it is winter, I take the subway in NYC so I have more exposure to germs, and that I traveled twice over the past 2 months for vacation and for Christmas. Perhaps this is just PEM from all of the things that have been going on. But it is significant enough that I am getting concerned.