Applying rubbing alcohol to your cold sore can help dry out the cold sore and help the cold sore heal faster.
You can also use hydrogen peroxide on cold sores as well which can also help dry out the cold sore and the cold sore should go away within 3 to 4 days when using either rubbing alcohol or hydrogen peroxide or even both.
Applying some toothpaste to the cold sore can also help dry the cold sore out and help it heal and go away faster as well.
Just be aware that for some people the rubbing alcohol or hydrogen peroxide can cause irritation and pain when applied to cold sores and if you do experience pain or other irritation then you should stop using the rubbing alcohol or hydrogen peroxide.
Cold sores when left alone and untreated will usually heal within 2 to 3 weeks but you can sometimes speed up the healing of the cold sores using some home remedies or using over the counter ointments.
Abreva is also another way of getting rid of cold sores.