Is there something I can do to cure a blister in the mouth? Any OTC meds that help?

Herpes treatment. Blister in the mouth may be herpes or cold sore. Herpes is chronic and contagious. It can be treated with oral prescription meds such as acyclovir, Valtrex (valacyclovir) or famvir. Topical otc creams such as abreva or Denavir or Acyclovir cream are meant to be used on the external surface of the mouth or lips. Topical anesthetics such as anbesol gel, blistex, camphophenique, herpecin-l, viractin help with pain.