Many of us have read horror stories online about traveling with breastmilk. I’m thankful to say I have not had any issues.
When traveling to Greece, we took several bottles of milk on the airplane. At security, the milk had to go through the X-ray machine. It was also tested with a special machine (but was not opened.) The precautions are necessary in today’s world. You could opt out of X-ray but then security will probably need to take a bit of your milk and test it. This probably takes longer so plan ahead if you are not willing to X-ray the milk.
I also traveled to Canada for a wedding (without my baby girl) and pumped while there. We stored the milk in a large cooler bag filled with icepacks. Throughout the trip, we made sure to get enough ice to keep the milk cold – at the wedding venue, at the lodge, and during sight-seeing trips. When going through customs, I told the attendant that I had a freezer bag full of breastmilk. She commended me on my breastfeeding efforts and told me to have a nice flight. I took the milk as a carry on. It arrived home still frozen.