Status effects

Status effects are temporary, usually negative, character modifications resulting from the character's interactions with the game, such as poisoning after getting hit by a radscorpion, or addiction after consuming a drug.

For a list of effects associated with critical hits, see critical effects.

Irradiation

Severity	Penalty
5%	-10 healing rate
10%	-5 Sequence
15%	-1 Charisma
20%	-1 Endurance
25%	-1 Agility
30%	-1 Perception
35%	-1 Strength
40%	-10% critical chance
45%	-1 to all SPECIAL attributes
50%	-3% to all damage resistances
55%	-3 to all damage thresholds
60%	-2% to all damage resistances (stacks for a total of -5%)
65%	-1 to all SPECIAL attributes (stacks for a total of -2)
70%	Maximum hit points reduced by at least 25%
75%	Critical chance set to 1%
80%	Healing rate set to 0
85%	Action points reduced by at least 50%
90%	-1 to all SPECIAL attributes (stacks for a total of -3)
95%	All damage resistances set to 0
100%	Hit points set to 1

Irradiation means radiation exposure.

Radioactive contamination builds up over time as you visit places with intense background radiation (such as the Glow or the Lost Hill bunker), get hit by attacks that expose you to radioactive particles (ELECTRO-RAD Rockets, Rad Shot, Aliens), or ingest radioactive substances. A status indicator will appear in the top‑left corner of the screen once there's enough radiation in you that it starts affecting your stats; mouse over it for details.

Any character can instantly become fully shielded from all radiation by equipping a suit of TMA Metal Armor. Failing that, the effects of radiation exposure can be mitigated by increasing your radiation resistance.

Radiation resistance reduces the dose of radiation you receive upon exposure by a percentage. It is governed by Endurance, which grants +2% radiation resistance per point (or 1% if you have Fast Metabolism).

Rad Resistance and Snakeater support perks grant 30% and 20% of radiation resistance respectively.

Rad-X grants +50% radiation resistance and increases its cap by 10%, allowing the stat to reach 100% (full immunity) but note that some types of radiation (such as that you get exposed to in the Lost Hill bunker) will penetrate a portion of your radiation resistance.

Characters overexposed to radiation suffer radiation sickness which leads to escalating penalties as radiation exposure continues.

The severity of your radiation sickness is displayed as a percentage when you mouse over the dosimeter badge that says "Radiated" in the top‑left corner of the screen. The sickness has twenty stages, as shown in the table to the left.

Radiation continues to build up until it reaches 111% but there are no additional effects associated with going past 100%.

Taking RadAway will reduce your current radiation level by 50%.

Radiation can be purged instantly by doctor NPCs that can be found in most major locations.

Weakness

Weakness is a stacking debuff that subtracts 1% from one of the main six damage resistances in a fixed loop: normal → laser → fire → plasma → electrical → explosive.

For example, if a character has 12 stacks of Weakness, each of its six main damage resistances is reduced by exactly 2%; removing one stack of Weakness in this situation (12 - 1 = 11) would restore 1% of explosive damage resistance to the character whereas adding a stack (12 + 1 = 13) would remove another 1% of normal damage resistance from it.

The following items interact with the Weakness mechanic:

• Med-Tec Antidote instantly removes all Weakness stacks
• Perception grants +1% chance to resist Weakness per point
• Electrical damage applies 20 - target's Perception Weakness stacks on the target
• Critical hits have a chance to apply Weakness to the target (ranged attacks aimed at arms only)
• More Critical Damage (weapon perk) allows your crits to apply additional Weakness stacks on your target
• Heresy Shot (Alien-exclusive weapon perk) applies 3 Weakness stacks on hit
• Leader (class perk) applies 2 Weakness stacks on NPCs with every hit
• Random Boy (class perk) has a chance to apply 50 Weakness stacks on the target when attacking without a combat timer
• Good Natured (trait) applies Weakness stacks to the character that has it when it kills an NPC

Addiction

Addicted characters suffer stat penalties when they're not under the effect of the drugs they're addicted to. Each drug has a unique addiction effect; see Drugs for details.

Characters with the Chem Reliant trait become addicted to the drugs they take automatically; everyone else is safe. To get rid of an addiction, you need to take a dose of Drug Antidote or reroll your character.