S.R.
Found this on the Abreva website under the FAQs...
Q.Who can use it? Is it safe?
A:Abreva can be used by adults and children over 12. Abreva is considered safe and well tolerated. Abreva should be used five times a day for up to 10 days. And because cold sores are contagious, you won't want to share your tube of Abreva with others. Doing so may spread the infection.
So unless your daughter is 12 or older, I wouldn't do it.