Health is the hit point factor that measures the survivability of the player, it decreases as the player takes damage from a number of sources such as: getting shot, hunger, anomalies...etc but is restored from eating food and using medical kits. Taking damage with low protection armors will also induce bleeding which slowly leeches health until stopped.
The player takes damage by: being attacked by characters, walking on most anomalies, falling from heights, bleeding, radiation poisoning, toxic gas poisoning and hunger. This is restored by using medkits, eating food stuffs, and using health restoring artifacts like the Soul and Kolobok. If too much damage is accumulated, the player dies and the game ends.
Bleeding usually occurs when the armor of the player is ineffective against the attacks. Such examples are being shot with rifle ammunition or being clawed out by mutants with low bullet proof and rupture protection respectively.
A blood-drop icon will appear on the player's HUD if they start to bleed, and the color of the icon denotes how serious the blood loss is. Here are the 4 stages of bleeding:
- Green - Mild blood loss. Can be quickly patched up with bandages or may heal itself on its own, given enough time.
- Yellow - Moderate blood loss. Health is sapped at a noticeable rate and may worsen if the wound was caused by a powerful hit. Is usually instantly healed with a single bandage.
- Yellow Orange - Serious blood loss. Health is sapped at an alarming rate and death is certain within seconds if not patched up immediately. Is very likely to worsen to severe blood loss if not patched up in time.
- Red - Severe blood loss. One can now hear their accelerated heart rate. Death will occur shortly if the bleeding isn't stopped. A player with full health suffering severe blood loss can die within ten seconds if the wound isn't patched up in short order.
When the player is bleeding, health is slowly drained away and may worsen into severe bleeding if not healed in time which drains health at a deadly rate, often killing the player if it isn't stopped in time. To stop bleeding, the most effective way to use bandages but Medkits, while slow and costly, can also stop the bleeding if enough are used. Using Army Medkits can instantaneously stop bleeding, apart from severe, which usually takes 1 more bandage to fully close up.
Hunger, or nourishment, is present in S.T.A.L.K.E.R.: Shadow of Chernobyl and S.T.A.L.K.E.R.: Call of Pripyat. Hunger was left out of Clear Sky. Hunger occurs when the player goes days on end without eating. The player's hunger is restored by eating food items such as: Bread, Diet Sausage and Tourist's Delight.
Hunger has two effects in both games: letting it slowly develop into severe malnutrition for too long will slowly cause damage and severely decrease the player's stamina.