Poison resistance

Poison Resistance is derived statistic in Fallout, Fallout 2, Fallout 3, Fallout: New Vegas, Fallout 4, and Fallout Tactics.

It reduces poison damage by a percentage as well as the chance to get poisoned.

Fallout, Fallout 2, Fallout Tactics

 * $$\text{Initial Level}=\text{Endurance}\times5$$


 * The Fast Metabolism trait sets initial poison resistance to 0.
 * The Snakeater perk increases poison resistance by 25% per rank.
 * The Vault City Inoculations perk increases poison resistance by 10%.

Fallout 3
Poison Resistance is also present in Fallout 3. It has a much smaller part than in the previous games since only a few enemies (Radscorpions chief among them) use poison.
 * $$\text{Initial Level} \%=(\text{Endurance}-1)\times5$$

Example: A starting Endurance of 5.
 * $$(5-1)\times5=20\%~\text{Poison resistance}$$


 * The Cyborg perk can increase resistance +10%.
 * The Survival Expert perk can add between an additional +2% to +6%.