It will eventually begin to break down. Keep it refrigerated at all times. It is much more stable before you reconstitute it. And yea, it’s usually mailed without temp control but as long as you keep the time as short as possible without refrigeration, you should be good. Once you get it to your home and you can control it, I would do everything I could to keep it fresh ! Thanks for coming back to ask this. I’d hate to see you spend the money it costs for high quality GH like this and then not get it’s full benefit.