I asked my gp jus the other day as I have a whopping cold sore. He said its fine for topical use, is just putting a little on your lip, it might be a prob if you were taking tablet form. If any it absorbed to your bloodstream its only a tiny amount, whereas a tablet is a lot more straight to your blood.
Also in last tri its fine anyway. I also looked up on here about it, and a lady said her midwife told it was fine, when they looked up all the ingredients there was nothing harmful.
Im using it, but just couple times a day.
pharmasist also said putting bit of aftershave, perfume, surgical spirit on it would dry it up.