Mrs 1DC and I travel a fair bit, she is diabetic and we both take a fair bit of medication. sometimes we are away for up to three months so the medication bag is quite large. We always carry everything in hand luggage, the insulin in disposable pens goes in up to 5 insulated wallets.The medicines are in a see through zip bag. we carry our prescriptions and a letter from Mrs 1DC's Doctor to confirm she is diabetic. We have never had to show the letter or prescriptions and in fact don't even bother to declare the medication now because we were always told it was OK..We do split the insulin between our two carry on bags but i usually carry the medicine, i suppose it would be more sensible to split that as well...