Red Cross/BSA Wilderness First aid is great for us amateurs (CPR is a required).
Boy Scouts requires it for adults going on High Adventures (https://flic.kr/s/aHsjBpLxDo
I carry my first-aid kit in a daypack (1/3 the pack) it goes with me on hikes. 1/2 major trauma 1/2 general medicine cabinet stuff (with first aid book)
*Gatorade - Great for dehydration of any form
*Clotcolth - Hope I never need it!
*Fiber pills - good for both problems - slows down things moving too fast, speeds up things moving too slow
*If you are away from medical services and with someone with sever allergies you need two epipens and benadryl (each pen is good for 15-20 min, benadryl takes 30 minutes).