A bit too much on and lack of sleep left me with a cold sore. I have tried many creams and natural remedies, but I've found one that seems to work best for me. While pregnant and breastfeeding I only used a plant based cream but now with kids in the house I do not want to pass it on. The trick is to not to kiss the kids and only touch your lips when putting on cream, then wash hands and not to share drinks and cutlery. All a bit annoying but usually it clears up fairly quickly.