[wahern]

In the United States, 325mg is the amount in a single standard OTC pill. People often take two pills because of the old doctor's adage, "take two aspirin and call me in the morning".

81mg is marketed as low-dose (aka "baby aspirin"--because of the size or dose, not because it's intended for babies) and often prescribed as prophylaxis. But that's not particularly relevant wrt the maximum safe short-term dosage. The worst part of a flu usually only lasts a few days.

Here are the label directions from a bottle of generic aspirin as shown on Amazon (GoodSense Aspirin Pain Reliever 325 mg Coated Tablets, 100 Count).

  Drink a full glass of water with each dose. Adults and
  children 12 years and over: take 1 or 2 tablets every 4
  hours or 3 tablets every 6 hours, not to exceed 12 tablets
  in 24 hours. Children under 12 years: consult a doctor.

That's approx. 4 grams/day for OTC usage.

[gerdesj]

So what we have learned here is that whilst many years ago 8-30+ g daily dosage was either routine or at least proscribed in some cases, the routine upper limit is now much reduced because the side effects of taking Salicylate in such huge doses are worse than the symptoms or conditions that it was prescribed for.

However, it may be possible that the stuff might (in huge doses) cure or at least reduce something even worse than its own side effects. Then you are in the realms of a simple risk assessment where the failure mode is pretty horrid but that has to be weighed up against the alternatives if they even exist - all of which ... well you get the idea.

(IANAD)