I dont know if they make any for kids. You could always check with your doctor. Maybe he can prescribe something. Also, they make those Sea Bands (pressure point bands). Maybe they would work, though they might be too big. They need to be tight.
You can give a child Dramamine. I bought for my kids before we left on our last cruise. We didn't need it though. It didn't bother them at all. Dramamine comes in pill form and chewable tablets( that's what I bought). NOt everyone carries the chewables. I had a hard time finding it. I eventually found it at WALMART. Hope you have a great trip!
Have a couple of back up plans. 1. If your child gets motion sickness when riding in the car or on an airplane then try the sea-bands , yes they work very well, pressure points. My girlfriend's son get severe motion sickness -he wore the bands on the cruise and had no problems at all.
2. If the seabands don't seem to be working go for the Bonine, i think it works better than Dramamine, ask the Pharmasist about dosage for kids. Have them take it at night to avoid the possible sleepy side-effects- keep taking it for a couple of days, back it off and see what happens, if your child still gets the "queezies" and that " I think i am going to throw-up" feeling, start on the Bonine again.
3. For the occassional mild queezie - have some ginger cookies, or a glass of ginger ale and get them outside into the fresh air. Keep them busy and active to take their minds off of the "feeling"