Anyone heard of this before?

Im bewildered. I can’t remember the name of it right now (I’ll be picking it up eventually just to have it on hand) but I was prescribed a medication today that they said I would take orally until after the baby is born. I’m 37 weeks.
I only remember them asking if I’m allergic to penicillin and if I’ve had a history of cold sores or vaginal herpes.

Ive had cold sores before but NOT genital herpes (tested quite a few times over the years).

They said since I’ve had a history of them that I should make sure to take the medicine. This is my third child and I’ve never heard of this before. Not sure it matters but I’ll be delivering ceserean.

Has anyone been told this before?