I mean the flight itself. We have something against nausea (Daedalon) and I am trying to find something for a stuffy nose but since I am more Canadian now than Hungarian I have some difficulty figuring this out. Any good tips?
You are better off asking a doctor this.
A child often needs medication labelled for children and it's important you do not give him an adult dosage.
Does your child have the flu? Or are you trying to pack medication 'just in case'? If he has a runny nose I would recommend a simple salt based nose spray, if he has no complications at all and you are just trying to prepare, don't bother.
Our four year old has two long haul trips under her belt (SE Asia to Africa, SE Asia to America). We don't take anything different for the flights than we take for a road trip.
She gets a little anti-nausea medicine before the flight (because as an infant she got car sick) and that's it. But we have been cutting that dose down each trip, come March when we fly to the states we will try without.
I don't give her any congestion medicine unless she was suffering from a head cold.
But for your child, a discussion with your family doctor is the best course of action, as your physician knows the child's weaknesses and strengths when it comes to health.