I keep Children's Advil (or Tylenol or Motrin) and Children's Benadryl in all my kits, with dosage instructions by weight.

Not directly on point re: the BOB, but in larger kits I added an over the counter inhaler (Primatine Mist) because we had a situation where one of our house guests forgot their son's prescription inhaler on one occasion. My wife suggested we stock the kits appropriately in case something like that happened again.