My husband and I always follow these rules:

 

1. If we go out with our daughter or she goes out with someone else, we never take all of her medication. We always leave some medication at home in case something weird happens (i.e. we or someone else misplaces her medication or something like that).
2. When someone else takes care of her (my mother, my in laws or her baby-sitter) we make sure to prepare her medication before leaving. We always mix her pills with a little bit of milk (to protect her  tummy), so we leave this preparation ready for the caretaker.
3. We sticked to our fridge a list of instructions in case something happens (if she vomits her medication, in case of an emergency, etc.). We give a copy of this instruction sheet to anyone taking care of her, if not at home.
4. Before leaving our daughter with someone else, we “train” him or her. We ask the person taking care of our daughter to give her the medication in front of us to make sure no preventable mistakes will be made. Only after being sure the person can do what we want, we feel comfortable.

 

I hope this helps.