The First Aid Kit is used to treat a character of all his/her injuries and sicknesses. It takes up 2 slots during scavenging.
It can also be brought along as expedition equipment in scavenging to prevent harm from the person that brings it (doesn't protect against death). It gets consumed after the expedition if used. In addition, it can be used to help the family sleep better (prevents sleep deprivation)
Repairable: Yes (with Bug spray and Boy Scout Book)
Tradable: Yes
It can also be used to heal Pancake the Dog during his 3rd time returning.
It can also be given as a gift to Mary Jane or Timmy as a birthday present.
Gallery
First Aid Kit's loading screen
A First Aid Kit hanging on the wall of the bunker
An empty First Aid Kit (Used)
The First Aid Kit's 3D model