Modify Game Attributes
     Use  a  text  editor  (such as NOTEPAD) to edit the "defuser.ini"
file in the "\EA games\harry potter and the chamber of secrets\system"
folder. Scroll down to the end of the file to find the following text:

[HGame.Harry] 
bInvertBroomPitch=False 
bAutoCenterCamera=True 
bMoveWhileCasting=True 
bAutoQuaff=True 
fDamageMultiplier_Easy=1.2 
fDamageMultiplier_Medium=2.0 
fDamageMultiplier_Hard=3.0 

     You   can   change   the   values   of  "fDamageMultiplier_Easy",
"fDamageMultiplier_Medium"  or  "fDamageMultiplier_Hard" (depending on
the level you have selected) to 0.1 to take less damage.

WARNING!: Always make a backup before overwriting game files.