Some attacks reduce the opponent's score in one or more abilities. This loss can be temporary (ability damage) or permanent (ability drain). Points lost to ability damage return at the rate of 1 point per day (or double that if the character gets complete bed rest) to each damaged ability, and the spells lesser restoration and restoration offset ability damage as well. Ability drain, however, is permanent, though restoration can restore even those lost ability score points.

While any loss is debilitating, losing all points in an ability score can be devastating.

• Strength 0 means that the character cannot move at all. He lies helpless on the ground.
• Dexterity 0 means that the character cannot move at all. He stands motionless, rigid, and helpless.
• Constitution 0 means that the character is dead.
• Intelligence 0 means that the character cannot think and is unconscious in a comalike stupor, helpless.
• Wisdom 0 means that the character is withdrawn into a deep sleep filled with nightmares, helpless.
• Charisma 0 means that the character is withdrawn into a catatonic, comalike stupor, helpless.

Keeping track of negative ability score points is never necessary. A character's ability score can't drop below 0.

Having a score of 0 in an ability is different from having no ability score whatsoever. A wraith has no Strength score, not a Strength score of 0. A clay golem has no Intelligence, not an Intelligence score of 0. The wraith can move, it just can't act physically on other objects. The golem is not in a stupor or helpless, but it has no thoughts or memory.

Some spells or abilities impose an effective ability score reduction, which is different from ability score loss. Any such reduction disappears at the end of the spell's or ability's duration, and the ability score immediately returns to its former value.

If a character's Constitution score drops, then he loses 1 hit point per Hit Die for every point by which his Constitution modifier drops. For example, at 7th level, Tordek is hit by poison that causes his Constitution to drop from 16 to 13. His Constitution modifier falls from +3 to +1, so he loses 14 hit points (2 per level). A minute later, the poison deals another 8 points of Constitution damage, dropping his score to 5 and his modifier to -3. He loses another 28 hit points -- for a total of 42 hit points lost because of an overall 6-point drop in his Constitution modifier.

A hit point score can't be reduced by Constitution damage or drain to less than 1 hit point per Hit Die. At 7th level, Mialee has 22 hit points when fully healed. Even if her Constitution score drops to 5 or lower, she will still have at least 7 hit points (less any damage she may take).

The ability that some creatures have to drain ability scores (such as shadows draining Strength or lamias draining Wisdom) is a supernatural one, requiring some sort of attack. Such creatures do not drain abilities from enemies when the enemies strike them, even with unarmed attacks or natural weapons.