I've had good luck using Apple Cider Vinegar to get rid of cold sores on my lip.
I take a cotton swab and soak it in Apple Cider Vinegar and apply the Apple Cider Vinegar to my cold sore 3 times per day and the cold sore starts to go away within a few days of doing so.
Apple Cider Vinegar is antibacterial and antiseptic which kills off the virus that causes the cold sores.
You can also apply some salt water to the cold sore as well which helps to get rid of the cold sore or even some hydrogen peroxide.
But in my experience Apple Cider Vinegar has worked the best for me to get rid of my cold sores and is what I now use when I have a cold sore.