SunshineA replied: "not sure, but try looking at the advice leaflet that you get with these. if your unsure try getting a natural lip balm/cold sore cure as this would be better.
Valtrex (valacyclovir hydrochloride) is generally considered safe for women who are pregnant. This is based on animal studies that looked at the effects of Valtrex during pregnancy (sorry this is the only information i could get a hold off)
your best of talking to a pharmacist"