Hit point

Hit points, also known as health points (or HP), damage points, or just health (among other synonyms), is a finite value used to determine how much damage (usually in terms of physical injury) a character can withstand. When a character is attacked, or is hurt from a hazard or fall, the total damage dealt (which is also represented by a point value) is subtracted from their current HP. Once their HP reaches 0, the character will fall unconscious and be unable to fight. In DDO, health is often abbreviated by two letter initialisms such as HP.

Unconscious
U18: Incapacitation has changed for characters who stabilize. Once a character stabilizes, a twenty second timer begins. If a character is still incapacitated when the timer runs out, the character will get up with twenty percent of the character's maximum hit points returned.

Increasing Hit Points
Hit points increase by themselves when you level up. That increase is not equal for everyone and depends on many factors. However, everyone benefits from the bonus 25 HP from the free Heroic Durability feat received at creation.

Class
Your Class bonus to HP (marked as "Base" on your Character Sheet) is calculated based on the class you have taken each level in.

Melees:
 * Barbarian: 12 hit points per level
 * Fighter: 10 hit points per level
 * Paladin: 10 hit points per level
 * Monk: 8 hit points per level

Casters:
 * Cleric: 8 hit points per level
 * Druid: 8 hit points per level
 * Favored Soul: 8 hit points per level
 * Sorcerer: 4 hit points per level
 * Wizard: 4 hit points per level

Specialists:
 * Artificer: 6 hit points per level
 * Bard: 6 hit points per level
 * Ranger: 8 hit points per level
 * Rogue: 6 hit points per level

Epic levels: 10 hit points per level

Constitution
Your Constitution bonus to HP is calculated by multiplying your character level with your constitution modifier. This is not a static value; it's continuously recalculated as your constitution modifier changes because of buffs or debuffs. A negative constitution mod (resulting from a constitution below 10) grants a HP bonus of 0.

At level 28, your Con bonus to HP is 28 HP (1 per level) per 2 constitution over 10 constitution (your constitution modifier). As an example, 22 con at level 28 grants 6*28 hp for a total of 168 HP: ((22-10)/2)*28.

Toughness Feat

 * Toughness increases your hit points by +3 at first level, and 1 additional hit point for each additional level for a total of 30 hit points at level 28. This feat can be taken multiple times, and the bonuses stack.
 * Epic Toughness feat adds 50 hit points. It requires a Constitution score of 21 and the Toughness feat.

Enhancements

 * Racial:
 * Bladeforged can get up to +20 HP from their Construct Toughness enhancement line.
 * Dwarves can get up to +30 HP from their Dwarven Toughness core enhancements, and Child of the Mountain can add up to 4% to their Maximum Health.
 * Half elves with Barbarian Dilettante can get up to +15 HP from their Improved Dilettante line.
 * Warforged can get up to +40 HP from their Construct Toughness enhancement line.
 * Barbarian:
 * Frenzied Berserkers can get up to +20 HP from their Toughness core enhancements.
 * Occult Slayers can get up to +30 HP from their Toughness enhancement.
 * Bard:
 * Warchanters can get up to +30 HP from their Fighting Spirit and Warmaster core enhancements.
 * Cleric and Favored Soul:
 * Warpriests can get up to +15 HP from their Toughness enhancement.
 * Druid:
 * Nature's Warriors gain +1 HP per Action Point spend on this tree.
 * Fighter:
 * Kenseis can get up to +15 HP if they choose Conditioning as their Ascetic Training enhancement.
 * Stalwart Defenders gain +1 HP per Action Point spend on this tree.
 * In addition, they can get up to +20% Maximum HP when under Stalwart Defense with their Tenacious Defense enhancement.
 * Monk:
 * Henshin Mystics can get up to +20 HP if they choose the Way of the Patient Tortoise as their Animal Forms enhancement.
 * Shintao monks can get up to +15 HP from their Conditioning enhancement.
 * In addition, they also can get a +3% Insight bonus to Maximum Hit Points if they train their Meditation of War enhancement, and are on Earth Stance.
 * Paladin:
 * Sacred Defenders gain +1 HP per Action Point spend on this tree.
 * In addition, they can get up to +20% Maximum HP when under Sacred Defense with their Tenacious Defense enhancement.
 * Wizard:
 * Pale Masters can get up to +30 HP from their Deathless Vigor enhancement.

Other bonuses

 * Characters can get +10 hp from Draconic Vitality, received by achieving 150 Agents of Argonnessen favor.
 * Characters can wear gear with properties from the False Life line of enchantments, for between 5 and 50 HP in increments of 5.
 * The Vitality item enchantment grants +20 or more hp that stacks with all other bonuses.
 * Green Steel accessories can give +10/15/20 hp for a total of +45 hp across the three tiers (Elemental Energy). Greater Elemental Energy (+20 hp) can also be found on the Alchemist's Pendant and certain sets of Dragontouched Armor (with a Sovereign Rune of Health added).
 * A guild augment Crystal of Health stacks for an additional +5/10/15/20 hp, depending on size. However, gear with Guild Augment Slots no longer drops as of U17.
 * Constitution item enchantments (called Health on random gear).
 * Note that items that increase your hit points directly (as opposed to increasing your Constitution) don't automatically give them to you; they merely increase the maximum possible. There will still be a hole left until you get some healing to top it off. These same items will also take the extra hp "off the top" if removed. Changes to your Constitution will indirectly, and immediately, increase (or decrease) your hp. In other words, a level 20 character with 480 hp who equips a Toughness item will be at 480/500 hp, while the same character who increases his Constitution by 2 points will be at 500/500 hp. Later, the same character removing the items while at 480/500 hp will then be at 480/480 after removing the Toughness item, or 460/480 after reducing his Constitution.

Temporary Hit Points
Some effects award a character additional, special hp called temporary hit points. Any damage the character suffers that would normally affect his real hp applies to his temporary hp first. As their name implies, they don't last forever -- only until they're used up or the buff that granted them wears off. Temporary hp appear as a number with a "+" sign, in parentheses, after the character's real hp count on top of his red hp bar.

Bonuses and penalties that affect healing amounts do not affect temporary hit point gains.

Some common effects that cause temporary hit points:
 * Aid/Mass Aid: +9-18 hp for Aid, +9-23 hp for Mass Aid, depending on the level of the spell.
 * Greater Heroism: +11-20 hp, depending on the level of the spell.
 * Life Shield: +15 hp for one minute.
 * Bodyfeeder: +15 hp for one minute.
 * Lifedrinker: +25 hp for one minute.
 * Demonic Shield: +30 hp, not removed on rest/quest entrance.
 * Concordant Opposition +30 hp.
 * A bard's Inspire Greatness song: +20 hp.
 * False Life spell - +13-20 hp. Note that this stacks with the more permanent False Life item enchantment.
 * Shroud of the Lich: +30 hp