Constitution

Constitution is one of the six character abilities. It applies a modifier to the character's class base hit points. This modifier applies to warrior classes for the first 9 levels and to other classes for the first 10 levels. For example, clerics get 1d8 base hit points per level. However, a cleric with Constitution 16 receives 2 extra hit points per level for a total of 1d8+2.

The effects of constitution are retroactive: When the constitution score changes, hit points are added (or substracted) for all the levels of the character.

The modifiers to hit points gained per level work in one of four different ways depending on the constitution score: This character ability is essential for all classes, but more so for fighters, paladins, rangers and barbarians. Paladins and rangers have a high minimal requirement for constitution.
 * Constitution 1-6: Penalty to hit points gained. The minimum hit points gained when advancing level is 0 (i.e. no change).
 * Constitution 7-14: No modifier. These scores only affect shorty saving throw bonuses for gnomes, dwarves and halflings.
 * Constitution 15-16: Bonus to hit points gained. Same bonus for all classes.
 * Constitution 17-25: +2 bonus to hit points gained for non warrior classes. Higher bonus for warrior classes except monks.

Characters with constitution 20 or higher regenerate lost hit points.

Gnomes, Dwarves, and Halflings get bonuses to saving throws based on their constitution, up to a maximum of +5 at 18 constitution. These bonuses are called "shorty bonuses". They are re-calcuated on level-up: If the constitution of a character changes, the effect on his hit points is immediate, but his shorty bonus will not be affected until the character levels up. Gnomes receive this bonus to their Wands and Spells saving throws, while Dwarves and Halflings both have the bonus added to their Death, Wands and Spells saving throws.

NOTE: The Baldur's Gate manual describes a "resurrection chance" based on constitution, but this is not actually implemented in the game. All characters, aside from the main character, can be resurrected if their body is salvageable (if the character's hit points have been reduced below -10, or they have been turned to stone and subsequently shattered they cannot be resurrected), regardless of their consitution score. On normal and novice difficulties, characters can still be resurrected even if their body is destroyed.

Permanent constitution boosts

 * Manual of Bodily Health in Baldur's Gate (game) and Baldur's Gate: Enhanced Edition
 * In Baldur's Gate II: Shadows of Amn, a +2 constitution boost is gained from offering a Tear of Bhaal in Hell by taking the Evil choice during the Test of Fear.
 * Machine of Lum the Mad in Baldur's Gate II: Throne of Bhaal
 * The Dragon Disciple sorcerer kit in Baldur's Gate: Enhanced Edition and Baldur's Gate 2: Enhanced Edition recieves a +1 constitution bonus at level 5 and 15.

Constitution altering items

 * Buckley's Buckler
 * Obsidian Ioun Stone
 * Malla's Soul Stone
 * Axe of the Unyielding +5

Temporary constitution altering items

 * Girdle of Fortitude
 * Potion of Fortitude