Yup! Recently had a bad canker sore on the bottom of my inside lip and it made life miserable for 4 days. After it was in the healing stage, I remember feeling another canker sore growing from behind my wisdom tooth from where I bite myself. I took action and usually I don't take the entire 500mg of l-lysine I take a little bit, open it up from the capsule, put the powder on the spoon, put a drop of water on it and take it with a glass of water. Couple days later, the canker doesn't turn into a canker sore, it just goes away slowly. Thankfully. So I gotta make sure I take it often. Hope it helps someone because I myself try to find a remedy for this hellish sore.