I have been wanting to try a 1.0 retinol for a while and thought my skin was ready for it. I do have to say that I could immediately feel this work. It did make my skin tingle and peel slightly. Now I can tolerate it very well and it goes on and spreads very nicely. I also can now use a small amount on my neck and chest area as well. One pump is enough. Sometimes I mix it with a different probiotic serum and that is an extra nice feeling on my skin.