So, you have a cold sore. Maybe it's your first one, or perhaps these pesky blisters make reoccurring appearances. Either way, the virus that causes cold sores is highly contagious, and you may be wondering when you can return to normal activities — like using your favorite lip balm or kissing your baby niece. Once you understand what makes cold sores contagious, you can know when your chances of spreading the virus decrease.
