Ok - I'm the one whose dentist suggested the Lysine supplements and had really good results. It's use in treating/preventing cold sores (herpes virus) is pretty well researched and is related to viral replication. For that reason, you do want to avoid arginine supplements and you may get more bang for your buck by taking it on an empty stomach (unless it bothers you). I think my dentist said she's taken as much as 6000mg a day. As long as you don't have other medical problems (esp. kidney - anything that requires you to limit protein), it should be safe.
When you consider that the vast majority of people have been exposed to the herpes virus, it could be an atypical presentation of herpes virus or a slightly different strain of virus. Stress can depress the immune system and trigger an outbreak. This is pure speculation on my part, but I did see improvements very quickly at 1000 - 2000 mg a day. Too quickly to attribute it to something else (even placebo effect, as I didn't really expect it to work). I did have to exfoliate/moisturize regularly for a while there, but at least my lips weren't peeling off while I was talking to people. (Does our waitress have leprosy? ICK!)
The first time I stopped taking it, the condition returned. I had to start again & up the dosage from 1000 to 2000mg a day to get it under control. After a few months at that level, I slowly lowered the dose and quit the lysine without relapsing. It's nice to know that it is helping other people, but still - it probably won't fix everyone. Thus far, it seems a lot more effective than most of the high dollar crap being marketed online.