@cathyf31 I started doing it because I travel in a van. I think the info on the box to keep it cooler than 73* or close, which isn't very warm. Think summer days when you have the windows open! I have saved all my pens ( I literally just finished), because, it was such a pain in the to get the refill from Accredo. They stressed me out, for months. Lot's of errors on their part, and of course, you can't miss a day. Sometimes the pen would come the day before I had to start a new pen. So, I kept the pens, in case they messed up. Yes, theirs plenty medicine left in each pen. I'm think 4-5 days??