I know that if I take damage, bandages and first aid kits can only get me back to 75% health, and after that I have to use something like an Energy Drink (which gives 40 boost) to fully heal, and it seems to do a heal over time effect, unlike bandages and kits which are instant (after the cast time).
Painkillers seem to be another boost item, and give 60 boost.
Does boost do anything besides beside cause the heal-over-time effect? How much can they heal?