Psycho Addiction

 is a form of addiction which can occur in Fallout, Fallout 2, Fallout 3 and Fallout Tactics.

Fallout, Fallout 2, Fallout Tactics
"You feel light-headed."

Using Psycho carries a 20% chance to become addicted. The addiction lasts for 1 week.

Fallout 3
Using Psycho carries a 10% chance to become addicted.

Trivia

 * The picture is a reference to the Friday the 13th and Nightmare on Elm Street movies (and possibly The Texas Chainsaw Massacre this is unknown due to the fact Jason (Friday the 13th) used a chainsaw in one of the movies.).