You gain a Bonus equal to twice the Tier of the potion on Fortitude saving throws and Flat Checks against ongoing Poison effects and Persistent Damage (Poison) for 12 hours. This provides no DR against attacks that deal Poison damage or inflict Persistent Damage (Poison), it only increases your body’s ability to shrug them off.
You can immediately make a saving throw or Flat Check against any Poison effect that you are suffering from when you drink this potion, without suffering any negative effects if you Fail or Critically Fail the saving throw.
At Tier 4 and above, the potion grants you immunity to the Venom condition for 12 hours.