is lysine safe in pregnancy?

I get cold sores sometimes and while I've not had any during this pregnancy luckily, I am thinking of stocking up on and starting to take lysine pills a few weeks prior to my due date as lysine has always helped clear up and prevent cold sores for me and I know how dangerous the herpes virus can be to newborns so would feel horrible if I got a cold sore and passed it on to my baby.