I used to suffer regularly with cold sores and lysine really does shorten the life of them. I was more likely to get an attack before my periods but since I've been post meno I've maybe had 5 or 6 attacks. (less than 1 per year). I just took the lysine during an attack - haven't even though whether they are ok to take TBH. I did try to take them regularly to try and reduce the likelihood of an attach when I was stressed, but I got some indigestion with them so I ended up taking them at the first signs of a tingle.
I had shingles a few years ago - in my left thigh & buttock (I know bit of an odd one). I was given anti viral tabs (I think acyclovir) which really did shorten the attack but gave me really bad headaches. I didn't take lysine then, didn't think they helped with the Shingles virus, so I don't know how much they would help. What I would say is if you're off work don't go back too soon. I only took 2 weeks off, and I really regret not taking the 3rd week as I was no where fit enough. I was a wreck at the end of that first week back.
HTH
S