The maximum number of Hit Points is 50, though both the Body Building and Flesh Rot skills increase the maximum to 60. Players with the skills Diagnosis (survivor) or Scent Blood (zombie) can see the HP values of survivors next to their names. Diagnosis carries over to one's zombie character.
Losing Hit Points
Characters typically lose Hit Points by being attacked by other characters. When a character successfully attacks a target, the target loses Hit Points equal to the damage the attack deals.
Survivors also lose Hit Points from being infected by a bite attack from a zombie with Infectious Bite.
Anyone with the Flesh Rot or wearing a flak jacket takes 20% less damage from gunshot attacks. Flak jackets will have the same effect on a zombie character.
Regaining Hit Points
As a Survivor
The most effective method by which survivors can heal themselves or other survivors (or zombies, if they so wish) is with first-aid kits, found mainly in mall drugstores, hospitals, and sometimes in churches. A first-aid kit grants 5HP to the person it is used on. The First Aid Skill allows survivors to heal 10HP with a first-aid kit. First-aid kits are at their most effective when they are used by someone with the surgery skill in a powered hospital or infirmary. This makes them heal 15HP. Healing yourself gives you no XP. Healing another gives 5XP, regardless of the amount of HP healed.
Another method of gaining HP for survivors is through beer or wine, that are found in pubs, clubs, and mall liquor stores, (wine is also found in churches) though these are inefficient, as they only heal 1HP per AP. Their only real use (apart from RP purposes) is to raise your health from 50 to 51, broadcasting the fact that you have body building to those with Diagnosis.
As a Zombie
Zombies with the skill Digestion can heal themselves directly in two ways: successfully using bite attacks, or by feeding on dead bodies. Both techniques restore 4 HP per success. When feeding, the dead body cannot be revivifying, and must have been previously fed on less than ten times.
If a zombie jumps from a tall building, they will not die. This cannot therefore be used as a method of getting back to maximum HP.