Bandages are used to heal your damaged limbs.
Using any bandage item will open the Limb Selection Menu where you can select what limb you want to apply your bandage to.
Limb Selection Menu in game
Crafting Recipe
Heal any damaged limb by 50%
Crafted amount: 4
Crafting Recipe
Fully heal any damaged limb to 100%
Crafted amount: 1
Crafting Recipe
Consume this item to fully heal all limbs to 100% while also curing any adverse potion effects (poison, wither, oozing etc.)
Crafted amount: 2