I'm taking 8,000mg famvir (generic) daily, but have only been on it a little over 3 weeks.
Initially I started with 500mg 4x/day. It caused migraines, nausea, body aches, and increased joint pain. After about 4-5 days, it calmed down. I gave myself a couple days and then increased to 1,000 mg 4x/day. Same thing happened with the side effects. And, again they went away after about 3-4 days. When I increased to 1500 mg 4x/day, I didn't have the reaction, nor did I when I went up to the 2,000 mg 4x/day. It has caused some GI distress but is tolerable as long as I eat with it.
Not sure if it's just the natural course of the disease, or if it was the IV saline that I started around the same time I started the Famvir, but I have been more functional the past couple weeks than I've been in the past 3 months when I was in a major relapse.