Loreal Excellence To Go is a newer product on the market. I have been trying different hair color. I used a Loreal product previously and decided to switch. Many hair colors cause an allergic reaction. I had a reaction to one of Loreal's other products but I really loved the color result. Loreal Excellence To Go claims that the color process will only take 10 minutes. This is totally correct. You will color your hair so fast. Makes it a quick job instead of an hour. Make sure 10 minutes only. Color will be darker with more time which it will wash out gradually as with most hair colors. I was impressed with the gray coverage. Usually with other hair colors, the gray would be lighter not fully colored. This product covers the gray completely. Satisfied with gray coverage. My hair felt soft and silky and shiny too. I chose medium reddish brown. Will try another color next time. As for allergic reaction, none. There is no heavy chemical odor. My head would itch after using some other products. I would have red, irritated skin. None with Excellence To Go. This product has a thicker texture so you may need two bottles for long hair. Loreal Excellence To Go makes coloring your hair a cinch.