Hydrolysis (reaction with water) of amides in acidic solution produces an amine and a carboxylic acid.
Hydrolysis of paracetamol (acetaminophen) in acidic solution produces an amine (4-aminophenol) and a carboxylic acid (acetic acid)
H 2 O/H 2 SO 4
| HO- C - C -H |
(acetaminophen) 4-aminophenol acetic acid
A person's history of taking paracetamol is somewhat accurate for the diagnosis.  The most effective way to diagnose poisoning is by obtaining a blood paracetamol level. A drug nomogram developed in 1975, called the Rumack-Matthew nomogram , estimates the risk of toxicity based on the serum concentration of paracetamol at a given number of hours after ingestion.  To determine the risk of potential hepatotoxicity, the paracetamol level is traced along the nomogram. Use of a timed serum paracetamol level plotted on the nomogram appears to be the best marker indicating the potential for liver injury.  A paracetamol level drawn in the first four hours after ingestion may underestimate the amount in the system because paracetamol may still be in the process of being absorbed from the gastrointestinal tract . Therefore, a serum level taken before 4 hours is not recommended. 
Untreated overdose can lead to liver failure and death within days. Treatment is aimed at removing the paracetamol from the body and replenishing glutathione .  Activated charcoal can be used to decrease absorption of paracetamol if the person comes to the hospital soon after the overdose. While the antidote, acetylcysteine (also called N-acetylcysteine or NAC), acts as a precursor for glutathione, helping the body regenerate enough to prevent or at least decrease the possible damage to the liver, a liver transplant is often required if damage to the liver becomes severe.   NAC was usually given following a treatment nomogram (one for people with risk factors, and one for those without) but the use of the nomogram is no longer recommended as evidence to support the use of risk factors was poor and inconsistent, and many of the risk factors are imprecise and difficult to determine with sufficient certainty in clinical practice.  NAC also helps in neutralizing the imidoquinone metabolite of paracetamol.  Kidney failure is also a possible side effect.