I'd say "sports drinks" like Gatorade would be the way to go. Gives the hydration of water with the electrolytes lost via vomiting. Grace had something like that a couple of weeks ago, and I plied her with Gatorade to prevent the dehydration. I don't know about the sugar content though. You might have to go with something like Pedialyte. They gave that to my Dear Old Dad when he was ailing.
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“Trouble rather the tiger in his lair than the sage among his books. For to you kingdoms and their armies are things mighty and enduring, but to him they are but toys of the moment, to be overturned with the flick of a finger.”
― Gordon R. Dickson, Tactics of Mistake
― Gordon R. Dickson, Tactics of Mistake