The other poster is correct, a dental dam etc... Also, as for is it safe at anytime and when is it active and dormant? Well the sure sign of being active is prodrome and blisters= outbreak. There can be viral shedding at anytime and no you won't know when this is..however you are on valtrex which is a supression medication in the way you are taking it and that greatly reduces its rate of spread. Basically there is always a chance that he could get it when he goes down on you, just the same as when you make love and are unprotected, if you do that is. I have type 1 genital herpes and my boyfriend goes down on me and things are fine. It depends, you should both do some research and talk about things. Good luck:)