I was on Valcyte for 3 years. I would not recommend that anyone stay on it for this long. It helped me tremendously, almost to the point of being normal. In fact, it worked so well, that I would push myself to the limit, relapse, and then sometimes increase the dose to the initiating amount to get back to my functioning level. The few times that I tried to go off of it, I relapsed, so I just kept taking it, knowing that you really aren't supposed to stay on it that long. I admit that I sound like a drug addict, but the idea of returning to my pre-valcyte CFS status was just too devastating. So I gambled, trading having my life now for the possibility that I could suffer adverse consequences at some point in the future.
And suffer adverse consequences I did. After I was on the drug for about a year and a half, I started having a lot of odd, seemingly unrelated symptoms. My once extremely curly hair turned straight and I started having gastrointestinal problems and pains in my abdomen. The problem was that my liver enzymes were fine, so I didn't attribute it to the Valcyte. Eventually my skin started changing, and I began to get severe headaches and have cognitive difficulties. I woke up one morning and had trouble walking and talking. It turned out that I had a tumor in my pituitary gland that started hemorrhaging. Still, my liver enzymes were fine, and none of the doctors could figure out what was going on. Things got progressively worse - I had severe trouble breathing, and skin biopsies indicated that I might have scleraderma (though the blood tests were negative). I hadn't wanted to go off the Valcyte during this time because I didn't want to have the CFS symptoms on top of everything else. Eventually, I tried going off the Valcyte because everything else had been ruled out, and I eventually recovered. I have been off the Valcyte now for a year and am still experiencing some of the effects, but the are gradually receding. The CFS symptoms have started to return, but I just have to deal with them at this point.
I'm not going to tell anyone not to take this medication. It gave me about two years of my life that I otherwise would have spent in bed. But it is a very potent drug and if you start experiencing ANY odd symptoms, you should stop taking it and see if they go away - even if your liver enzymes are fine. I definitely wouldn't recommend taking it more than a year and a half, although I think each of us needs to make our own decisions about what is best. I know what it's like to be desperate to get better, but sometimes we just have to suffer through it and hope that there will be better treatments in the future. Unfortunately, I had to learn this the hard way. At least I am now more optimistic about the future than I was before. The fact that the Valcyte did help me is a positive sign that whatever this is can be treated. And it seems that the scientific research in this field is progressing at a rate heretofore unseen. I do believe there will be an effective treatment within the next five or ten years. So at least I now have something to help me get through that I didn't have before: hope.
Best of luck to you!