[shabble]

Are you talking about 3.5g Tylenol (Acetaminophen/Paracetamol) in conjunction with [moderate to large] amounts of alcohol? Because otherwise, it's unlikely to be fatal even in a single dose, and is within normal dosage guidelines for daily use (typ. 4000mg/day)

It takes somewhere around 10g in a single dose, or 6g+ repeated over several days to cause serious damage[1], although obviously it varies by individual.

Note: This is not to downplay in any way the seriousness of APAP/Paracetamol toxicity, it's [iirc] the 2nd most common drug of fatal overdose, and is a truly horrible way to die[2].

[1] https://en.wikipedia.org/wiki/Paracetamol_toxicity

[2] Although prognosis is good if you get proper treatment in ~8hrs.