Addiction

Addiction is a group of negative effects acquired from repeated substance use. It represents a dependency to a substance, or activity, meaning that one's body (or mind) is in need of a regular dose in order to avoid withdrawal symptoms.

Overview

 * Addiction can happen from using too many chems. An addict suffers withdrawal symptoms that can cause ill effects when a drug wears off. Many substances in the Fallout games are addictive. Each chem has a chance of addiction. One of the most addictive chems is Jet.
 * For Fallout 1 and Fallout 2, withdrawal effects occur after becoming addicted and going for some amount of time without using that chem. For non-Jet addictions, addiction lasts seven days from the onset of the withdrawal effects (nine days of non-use), while Jet addiction can only be cured with the Jet antidote.
 * Certain NPCs have addictions, not just the player character.

Types of addiction

 * ¹All alcohols are flagged to use this addiction in Tactics, but have a chance of 0.
 * ²Only used in game files; possible bug.
 * ³Cut from the game.

Fallout and Fallout 2
Selecting the Chem Resistant trait results in a 50% resistance to the addictive effect of individual chems, while the Chem Reliant trait doubles it, but with faster recovery. Chems which normally have a 10% addiction rate will be reduced to a 5% rate. If the trait is taken, however, chems will only last half as long.

Fallout Tactics
Unlike Fallout and Fallout 2, chems do not have an addiction delay, instead immediately applying the effect after the chem's duration has expired. The Psychotic perk reduces the withdrawal effects from Psycho, while the Chem Resistant and Chem Reliant traits behave as they do in the previous games.

Alcohol addiction is present in Tactics, but is completely cut: all beverages that could provide it instead have zero addiction chance and no penalties set up, instead giving an unseen Drunk status for 1 minute. Happy Pies were also set up to be addictive, however the effect was left disabled in the final game with a chance of 0%. While Mutie has an addiction, it will not indicate the player is currently addicted outside of the stat detriment due to no indicator flags being set up for it. Given it shares the same effect and duration as RadAway, this may be an unintended bug.

Fallout 3
In Fallout 3, addiction is permanent. It can, however, be cured for a price in caps by visiting a doctor (like the one in Megaton). Owning a house in either Megaton or Tenpenny Tower enables no-cost addiction removal if the My First Laboratory house improvement is installed. Also, the healing archways in Mothership Zeta include removing addictions as part of their healing effects.

In addition to standard addiction chance, certain items have an additional tracker value which builds up with each subsequent use of a substance. Internally, this effect is referred to as the "Usage Monitor Effect," or "UMON." Each use of an item adds its UMON value to the total UMON value and remains a part of it until its specified time limit elapses, at which point it is removed from the current running total. The accumulated value of 75 seems to equate to an additional 1% chance (added on top of any existing addiction chance), whereas a value of 175 seems to be equivalent to a 100% chance.

Items not listed in this table are not addictive in Fallout 3; this includes Rad-X, RadAway, and some other substances. Risk is a base chance of addiction per use, and only applies to alcohol items in Fallout 3. UMON is an accumulating chance of addiction. See Usage Monitor for a detailed explanation. Duration is the length of time required to pass without consuming the drug for the accumulated UMON value to be reduced.


 * ¹Only applies to plain Mentats, the other variations (Berry Mentats, Orange Mentats, and Grape Mentats) are nonaddictive.
 * ²Only applies to plain ant nectar, the other variation (Fire ant nectar) is nonaddictive.

Fallout: New Vegas
New drugs and addiction-causing substances are found in the Mojave Wasteland. Addiction is permanent unless seen to by a doctor. Fixer will remove the player character's addictions permanently, the only drawback being the application of a temporary "nausea" debuff. With Old World Blues, the Sink Auto-Doc cures addictions for free as part of the basic physical exam. The Logan's Loophole trait prevents addiction entirely at the cost of limiting the Courier to level 30. Perks in Fallout: New Vegas such as Chem Resistant, Brainless and Old World Gourmet reduce addiction chance.

Bugs

 * Addictions in effect at the conclusion of the add-on Dead Money may become incurable.
 * Fixer can permanently remove addictions due to a scripting error.
 * Ant nectar addiction used to be incurable due to a bug, but this was fixed in Fallout: New Vegas patch 1.2.0.31x. The console command will immediately remove the addiction on the PC version.