If someone has a cold sore and that cold sore is still contagious then when you kiss the person with the cold sore you can expect to get a cold sore yourself within 1 to 3 days after you kiss the infected person.
When someone has a cold sore and that person is contagious with that cold sore you should avoid kissing the person until the persons cold sore is gone and they're no longer contagious.
If you have a cold sore you can apply some toothpaste to the cold sore or even some baking soda paste which will help it go away.
Another remedy for getting rid of a cold sore is to apply some tea tree oil or apple cider vinegar to the cold sore and it will go away within 4 days.