I used an entire 400ml bottle of Immunecel Treatment in less than a month! I bought several empty bottles and filled them with the product so I could use it in different ways. I can use it on my back, spray it on my face after washing it or before I put on makeup, and even carry it with me to use from time to time. I put a lot of the product on a cotton pad and use it like a sheet mask and also use it like a wiping toner. It has the best utilization because of how large it is.