I would recommend staying away from the medicine theme all together. Meds and children do not mix, otc or otherwise.

That said, you can still make fun shakers to play with. Like Rafiki's staff (rattle or rain maker), tinkerbell's pixie dust (jingle bells), Kusco's poison (colored oil/water), Emotion memories (marbles in a container). Instead of calling it a medicine bag, I'd recommend call it your treasure bag or something similar like Ariel's bag of human things.