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 last for 1 week.

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

'Psycho' may be a reference to the drug Valkyr from the movie/video game 'Max Payne'. Max's wife was a doctor working with the pharmacudical company Aesir which developed a drug that increased a soldier's moral and will to fight. the description of Psycho is similar, along with the report documented in Operation: Anchorage, which describes the addictive properties and the effects of withdrawal on the test subjects.