so a cold sore surfaced today (no wonder, i had really chapped lips lately and have been especially stressed), and my mom told me to take 2 of these 1 gram valtrex pills in the morning, and 2 again tonight. i know i took them on time, because i woke up today with no sore, and then around 11am my lip tingled and itched and it looked slightly pimply. i took the pills at noon.

how long will it take for the medicine to work? will i still get a cold sore, just a less severe one? also, if it DOES disappear, how long until i can kiss my boyfriend, so that he wont get it? (because i hear the virus is there even if theres no sore)

You should see results immediately. If you caught it early enough, the sore shouldn't form. So long as a true cold sore doesn't appear you should be safe from spreading it to your boyfriend by kissing. What makes cold sores contagious is mostly the fluid or pus from inside the sore. Therefore, if your cold sore doesn't form enough to contain fluid it should be okay.

Of course, you're right there's no guarantee but I'd say the odds are heavily in your favor.

I'm in the same boat as you. I take valtrex when I feel one coming on and it usually shut's it down prior to forming. Sometimes a tiny bump still forms where the cold sore was going to be, but no fluid inside.

thanks for the reply :)
its been two days, and its practically gone now. A small "bubble" did form, with clear fluid in it, but its much smaller than it *would* have been (and i woke up today and it was gone).
thank goodness for valtrex.. because my cold sores usually last 2 weeks and are really embarassing and painful, and they are always in the middle of my lip.