First Aid is a mod that aims to revamp the minecraft health system for players. It adds a "part system", so your feet, hands, head and torso have their own health.
You can heal your body by appying bandages or plaster (just right click), or you can use (when activated using the config) other vanilla items or even (if enabled) the natural regeneration. If a part is in a bad condition, debuffs may be applied, or you might even die because of a critical part's health to drop under zero. These effects (except death) can be suppressed by morphine for about 5-7 minutes.
Since version 1.3.0, this mod uses a sound from this website. It is licensed under the Attribution 3.0 license.
This mod disables vanilla health regeneration by default. This effect stays even if you remove the mod. It can be changed in the config or by typing /gamerule naturalRegeneration true.