To use peroxide you use equal parts peroxide and white milk of magnesia and then thicken to a paste with corn starch. This will be applied to tear stained area and won't run into her eyes because it's too thick. After this dries you brush it off. I tried this a couple times and didn't notice much difference. I'm currently using a powdered supplement you add to their food once a day. It's like "Angel Eyes". This also takes a long time to work. My daughter used it for 6 weeks on her dog before the stains were gone. I'm also using Tums. Another member told me she got rid of tear stains by giving her Bully 1/2 a Tums in the am and 1/2 in the pm. I think any method takes a while. So just be patient and keep treating the stains and they'll eventually go away.