Here's ours - I am not expert on the regulations, but this works for us and I have it in writing from my admin.

OTC meds - we have an annual permission slip/release form that allows us to give OTC meds for minor situations (advil, benadryl, etc) when off-campus for band events. I have a small number of kids whose parents did not authorize that for whatever reason, or have allergies, we know who they are (and 99% of the time the kids know their own allergy situation). This applies any time we are doing band things and the nurse isn't available, including after school, football games, other local field trips.

Prescription meds - parents send the meds in the original container with prescription label and a note describing the dose and frequency. HBD holds all meds and distributes them as needed. If we have a parent with medical background on the trip, I usually defer to them. We only do this for overnight trips.