It is L-Lysine Oral Gel. The brand I use is called "Viralys" and I buy it on
Amazon. The vet did give it to me the first time, but it's cheaper and the same thing on Amazon. The vet told me to start with putting a little on his nose so he can lick it off and get used to the taste. I did that for a couple of weeks (I think) and then started putting about one squeeze lol on top of his food. I'm pretty sure the vet said an 1/8th of a tspn. He runs right to it even now and licks it right off lol.
I did this until his eye wasn't red and runny anymore. Once it cleared up she told me that he would need this about once a week for the rest of his life to keep it from coming back. Sometimes I don't do it as often as I should and I can see his eye start to run a little or get squinty.
Aren't you glad you asked? I talk just as much as I type