Some people swear by L-Lysine for cold sores but Ive yet to try it. I found a tip from a beauty magazine that works pretty good to keep it small, or at least keeps it from getting bigger once its there. Get a cotton ball and saturate it with acetone, nail polish remover works too. Get one end as pointy as you can and get it wet, and hold it on the cold sore for 5 to 10 minutes. You should start to feel that tingly sensation that you get when cold sores on your lip get big and uncomfortable. Hold for at least 5 minutes, I hold it for a little less than 10 minutes until it almost starts to burn. Once/if I feel the slightest burn I take it off, and wash my mouth off. Keeps them small and way less noticeable and theyll be gone in a couple days instead of a week.
You may have to redip the cotton ball to keep it saturated a couple times. Make it as pointy as you can and try to apply only to the cold sore, do your best to avoid touching the surrounding smooth lips or else that skin dries out too and gets red, making the cold sore more noticeable. After 1 or 2 tries I got it down near perfect. I havent had one of those big swollen embarassing sores in a very long time thanks to this trick. You still have a tiny little cold sore that people may notice but its better than those big old tingly ragers that everyone stares at.
Please note I do not have genital herpes, just the viral variant that causes cold sores. I wouldnt go about putting chemicals into those open sores that full blown herpes sufferers sometimes get on their face.
Valtrex stops cold sores dead in their tracks and is really the best option hands down. Sadly many people dont see doctors due to embarassment/access/insurance etc. I recommend trying your absolute best to get at a doctor for a Valtrex prescription because cold sore scarring around the lips is permanent and very embarassing as you get on in years. I got it from my mom as a child and have a bit of scarring, not terrible or anything but its there and I dont like it. My mom is almost 50 and she has a permanent white ring around her mouth plus decades of scarring, hate to say it but its very visually unappealing, thats putting it nicely. Just relaying my experiences, good luck.