I have had cold sores for years and break-outs quite often. I finally found a "solution" and I thought you might like to hear it. Yes, the sun, stress, caffeine all trigger cold sores. What I do is take 250mg of L-lysine (you can find it with the vitamins in most stores). I have waaaay less break-outs with this alone. THEN, if I should so happen to feel a little pain on my lip somewhere, like the beginning of a cold sore, or feel a tiny bump, I bump up the L-lysine dosage to 1000mg, and I take two a day for a few days. AND I immediately put a topical ointment which my doctor gave me that is called "Zovirax". It is 10 times stronger than Abreva or anything over the counter. If I catch the cold sore soon enough and put the Zovirax on it a few times a day for two days, it never has a chance to get big and out of control. Let me warn you though, because the Zovirax is so potent, if you use it too much, it can dry out the cold sore too much and cause it to bleed as it's clearing up. So when it feels like the pain of the cold sore is very minimal, stop using the ointment. I hope this helps. It's been a God-send for me.