Bonjela invisible cold sore cream is an effective way to treat cold sores and prevent them reoccurring this cold sore cream contains a cream based on the active medical ingredient uv active which is effective against cold sores caused by herpes simplex virus type 1 hsv 1 it creates a protective film layer on the skin cells of the cold sore and prevents attachment of virus particles to the cells additionally it protects the skin against harmful environmental stimuli such as uv radiationsui