Ughh, I hate cold cores. I always get them from illness, stress or the sun. I am vigilant about sunscreen on my lips all year long(has really helped my formerly chapped lips too! Bonus.)I have Zovirax and it works pretty well-cuts down the healing time a lot.
I was at my sons preschool the other day and one of the moms had her older son with her. He had a horrible breakout of cold sores all around his mouth and she was telling us how he's not allowed at school until it goes away. One of the other moms hadn't heard the whole story, so she asked what was wrong with him and his mother answers, loud as anything"He has herpes" I almost fell over!! The poor kid-he was about 8 or 9-old enough to be mortified.