I normally use natural toothpaste, but ran out of my brand. There was a tester of Aquafresh in the medicine cabinet, so I used that for about 5 days. After using this product for that period, the skin inside my mouth started to feel rough, and I began to develop irritation and canker sores. It also diminished my sense of taste. I stopped using the product and after a week the roughness went away, but my mouth is very sensitive, and I still can't tolerate any minty, cinnamon-y, or spicy foods. I have a very sour taste in my mouth, and my tongue is still red from irritation. This product should come with a very strong warning label, and I should have stuck to natural products.