Interesting. I have used a different home remedy for cold sores. I get a cotton swab, saturate it with classic Listerine, and daub the sore to get it thoroughly wet with the Listerine. This will sting (it is working). Do this for a few days and the sore dries up. But that is the point: Listerine has ethyl alcohol, an antiseptic. Its antiseptic action is from the solubility of the alcohol with the water in the cell, leading to the desiccation of the cell. Listerine also has eucalyptus and some other ingredients that may be helpful to this end.