Needs review
Source: Complete Warrior

Description: You cause intense pain in an opponent with a successful stunning attack.

Prerequisites: Base Attack Bonus +2, Stunning Fist, WIS 15

Victims of a successful stunning attack are subject to such debilitating pain that they are nauseated for 1 round following the round they are stunned. Creatures that are immune to stunning attacks are also immune to the effect of this feat, as are any creatures that are more than one size category larger than the feat user.