slide 2 of 12. Skin The skin is the largest organ in the human body. Its main job is to maintain the body's temperature, which means that sweat is created to cool the body, and goosebumps or raised hair occur to trap heat in the body. Along with sweat glands, the skin contains oil glands.
...However, if I am wrong about that, the answer is that acetaminophen (and its metabolites) are identifiable for up to 48 hours after you took the pill. Less if you took tiny doses, but up to standard clinical doses (<8g), it's 48ish hours.
The recommended daily adult dose for acetaminophen is four grams (4000 mg), or 1000 mg in a single dose. If you are taking other medications that contain acetaminophen, make sure you know the amount of acetaminophen they contain, so you stay within recommended levels and avoid liver damage.