Treatment with activated charcoal should be considered if the overdose has been taken within 1 hour. Plasma paracetamol concentration should be measured at 4 hours or later after ingestion (earlier concentrations are unreliable). Treatment with N-acetylcysteine may be used up to 24 hours after ingestion of Paracetamol, however, the maximum protective effect is obtained up to 8 hours post-ingestion. The effectiveness of the antidote decines sharply after this time. If required the patient should be given intravenous N-acetylcysteine, in line with the established dosage schedule. If vomiting is not a problem, oral methionine may be a suitable alternative for remote areas, outside hospital. Management of patients who present with serious hepatic dysfunction beyond 24h from ingestion should be discussed with the NPIS or a liver unit.
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.
For a common person with an overdose of paracetamol it is best to visit the doctor and seek immediate advice. If you are someone you know has had an overdose of paracetamol then whether to not symptoms start to surface you should visit the doctor. Earlier the better. Best within one hour of intake of it. And starts getting really dangerous after 24 hours of having taken he overdose. No self medication, no taking cues from people who have experienced this horror before or checking out the net for immediate assistance. Keep it simple. VISIT THE DOCTOR.