My experience with Herpes Zoster is that it recurs every 2 months. Accepting that excessive stress brings it on, could it be that if my stress is not reduced, the beneficial effect of acyclovir terminates after about two months when Herpes Zoster can then strike again? I have had 5 outbreaks, separated by 2 months each. This started after a major change in my life circumstances which has brought on a lot of stress the sources of which still persist.