bought from J.Crowe or on Amazon–I use the 5% solution–I add three droppers full to water and irrigate my gums with it using a plastic dental syringe [also on amazon] with a curved tip–The 2% I use to INSTANTLY cure canker sores whom I get a once or twice a year….once I had an infection–It was on the left side of my neck a few inches below my ear–I can’t complete a course of antibiotics because after 3 or 3 days it spikes my tinnitus to an unbearable level–the infection looked like a small bill [but it wasn’t]–so every 1/2 hours I applied directly on the lump 2% lugpls with a Q-tip–The infection went away–hard to believe a topical application could cure such a thing—I have heard that taking a few drops in water orally is good for cold or flu.