I guess I was splitting hairs some there in meaning that it's not like a side effect as in "this med can give you nausea, vomiting, and diarrhea" or "this med can cause ringing in the ears and blurry vision" if it's something for say depression.
That is happening because it is, for lack of a better phrase/term/understanding, "stirring up" the virus. It is directly affecting it and yes I suppose it would be called a side effect, but it's not unrelated to it's direct mechanism of action. I feel the first response to your post was saying this was just some "side effect" like an anti depressant causing erectile dysfunction. Something wild and wacky and partially unrelated to it's target site.
I would stay at the same dose, I think it is par for the course. At this level of understanding and scant / scarce information on what is actually happening and what to expect, it's hard to say. I've heard it said that it needs to stir it up so it can carry it away, I've heard it's an unintended consequence since what you want to do is suppress the virus (EBV at least) so it cannot spread any longer and when the cells it inhabits die off, the new ones will remain uninfected, subsequently decreasing your viral load. You can look around and you'll see different accounts of this with people taking anti virals.
I don't think anyone knows what is really going on.
All that I found for certain was that over many months 3,6,9, even 12, eventually you will begin to feel better if you're on the right anti viral, which if it's doing that I would say is at least an indication that it is affecting an area related to the virus and if it were me I'd probably keep taking it.
This is for Epstein-Barr I'm assuming?
Living Dead is right, you literally cannot herx on anti-virals by definition. You can experience an unpleasant temporary effect but it is not what a herxheimer reaction is. It is its own thing. For purposes of discussion it's a relate-able term but the viruses don't die off and release waste products. They merely quit spreading and lie dormant over time. I do believe his is mistaken in that it again is a conventional "side effect" but the ideas kind of overlap.
Anyway, I'd keep taking it and take it as a positive sign.