Although children with ADHD may seem to be inherently anti-structure, they actually function best in a structured, familiar setting. But vacations and travel are all about getting away from the familiar - new places, new schedules, new people. As the parent of a child with ADHD, you probably know that this is a recipe for crankiness at the very least and meltdowns at the worst. There are some steps you can take to mitigate the impact that travel will have on your child's behavior.
Planning the trip
Children with ADHD can get anxious and overwhelmed in new situations. You can alleviate a lot of your child's anxiety by including him right from the planning stage of the trip. If you've already chosen a location, ask him what kinds of activities he'd be interested in.
Use visual aids as much as possible - many people with ADHD are very visual. Show him pictures of the place you'll be staying, and find your destination on a map. Use a calendar to mark off the days until your trip.
However, make sure that you do not work your child up to a fever pitch, or else school is going to be difficult both for the child and her teacher. That may sound silly, but even children without ADHD can get so excited about an upcoming event that they can't focus or have behavioral problems, and children with ADHD are already on that setting by default.
Behavior on the trip
It's hard for your child to behave if she doesn't know what the rules are. She already knows the rules for home, school, playdates, etc. But you can't assume that she'll know how those apply to these new situations. Spell it out a couple of weeks ahead of time, and then again on the day of the trip. For instance, "Use your inside voice when we're in the airport and the airplane."
Also, make it clear that the usual house rules apply even when you're not in your own home. That way he'll know that there's no jumping on the bed, for instance, even if it's a bed in a hotel room.
Remember that you may not be able to impose the same consequences that you do at home, so figure out beforehand what they will be and communication them to your child.
When you're on your trip, be sure to use praise, with specific examples, to reassure your child that her behavior is on track. "I really appreciate how you played quietly with your toys when we were waiting for the plane."
Keep as much of your routine intact as possible. Try to keep mealtimes, bedtimes and medication times about the same as they are at home. Children with ADHD really need that consistency to stay on an even keel. If it's not feasible to have the same bedtime your child has during the school year, then try to keep the bedtime consistent through your vacation. If your child is hyperactive, it is essential that he get enough sleep. Some people assume that lack of sleep turns children into little zombies, but it actually can make them more hyperactive.
If your child has trouble falling asleep in a strange bed, try to replicate the home environment as much as possible. I bring the lullabies that my son falls asleep to at home with us when we travel. If your child has a favorite stuffed animal or blankie, this is not the time to decide that he or she is too old for it - bring it along.