RadAway Addiction

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

Fallout, Fallout 2 and Fallout Tactics
Using RadAway carries a 10% chance of becoming addicted. This addiction causes you to "feel nauseous" and reduces your radiation resistance by 20 for 10 days.

Fallout 3, Fallout: New Vegas
There is no RadAway addiction in Fallout 3 and Fallout: New Vegas.