The antidote works best hours before an overdose feels like anything
Liver injury followed in 6.1% of 2,540 treated patients when the antidote started within 10 hours, and in 26.4% when it started at 10 to 24 hours.
What the study found
The antidote's window closes while the person still feels fine
Among 2,540 treated overdose patients, liver injury followed in 6.1% when acetylcysteine was started within 10 hours and in 26.4% at 10 to 24 hours. Starting at four hours was no worse than starting at once. Acetaminophen labels warn that medical help matters even when nothing feels wrong.
The caveat · No control group, and from 1988
This was an open treatment series with partly historical comparisons, because withholding an antidote to build a control group was not available. It dates from 1988 and the regimens have changed since, most notably to a shorter two-bag drip. The time bands rest on when people said they took the tablets, which is unreliable after an overdose and missing altogether when doses were spread across days. What survives all of that is the steepness of the gradient, which later guidelines reproduce.