I ordered this for our 9 year old son who has ADHD and was gnawing on his fingers nonstop. Poor guy. We had tried everything else and nothing worked. We talked about using this product and how it would help him. He told me, "Okay, I'm ready." I applied this one time. He accidentally tasted it putting food into his mouth. He drank about 5 glasses of water and yelled about how bad it was.... we are now 4 weeks later. His nails are growing. He hasn't bitten them since. I am overjoyed. The bottle is sitting on the counter and I wouldn't hesitate to use it again. I haven't needed to. When you apply it, it has the appearance of clear nail polish and leaves a shiny finish -- I think that helped him remember, because he could see it. Amazing.