Synthetic Anesthetic and the like say "a single dose has a difficulty of X, while two or more have a difficulty of Y" or "any sized dose has a difficulty of X" but what about dose size in relation to the effects? For the Synthetic Anesthetic, it deals 5 Strain on a failure. If you use two doses, does that double?

Also, setting difficulty for detecting them in a drink or food. I thinking something like [base difficulty]-dose+Setback for modifiers.

Asked my wife (GM and former EMT). She says that a double dose of the same poison will increase the severity of the reaction and speed up the onset of symptoms if not treated immediately. She suggests running it as double severity and half the time to onset of symptoms. So yes, double strain and you PC has less time before symptoms become severe/untreatable.

We agree that you should decrease the difficulty to notice as it is a double dose and any flavored poison will be more noticeable. [base difficulty]-dose+Setback is a good way to run it.