Why Paracetamol Is So Dangerous in Overdose
In normal doses, paracetamol is metabolised safely by the liver. In overdose, a toxic metabolite (NAPQI) overwhelms the liver's glutathione stores and starts destroying liver cells. The dangerous part: people often feel fine for the first 24 hours while silent liver damage occurs.
Emergency — Call 999 / 000 / 112 / Poison Control NOWIf you or someone has taken more than the maximum dose (>4g in adults, >60 mg/kg in children), go to A&E IMMEDIATELY — even if feeling well. Do not wait for symptoms. The first 8 hours are critical for the antidote to work.
Timeline of Paracetamol Overdose
| Time After Overdose | What's Happening |
|---|---|
| 0–24 hours | Often no symptoms — nausea, vomiting may occur |
| 24–72 hours | Liver enzymes (ALT/AST) rise dramatically — may develop right upper abdominal pain |
| 72–96 hours | Peak liver damage — jaundice, confusion (encephalopathy), coagulopathy |
| Day 4–7 | Either recovery begins OR acute liver failure develops |
| Week 2+ | Full recovery in most; liver transplant required in severe cases |
Blood Tests Used in A&E
| Test | Purpose |
|---|---|
| Paracetamol blood level | Plotted on a nomogram to decide if NAC is needed (4h post-ingestion) |
| ALT / AST (liver enzymes) | Monitor liver damage — can rise 100× normal |
| INR / prothrombin time | Measures liver's clotting ability — most sensitive marker of liver failure |
| Bilirubin | Rises when liver fails to process it |
| Creatinine / eGFR | Renal failure is a serious complication |
| Blood glucose | Hypoglycaemia is a sign of severe liver failure |
Always Go to A&EEven if you've taken 'only' a few extra tablets, even if you feel fine, go to A&E. There is no visible sign of early paracetamol liver damage. The antidote (NAC) is highly effective if given early.
Is paracetamol dangerous at normal doses?
No — paracetamol is very safe at recommended doses (max 4g/day in healthy adults, 3g/day if drinking alcohol regularly or have liver disease). The risk is in overdose.
Can alcohol increase paracetamol toxicity?
Yes. Chronic alcohol use increases NAPQI production and depletes glutathione. Heavy drinkers may develop liver damage at lower doses than average. The safe daily limit for regular drinkers is 2g (2000 mg).
What is NAC and how does it work?
N-acetylcysteine (NAC) replenishes glutathione stores in the liver, allowing it to safely process NAPQI. It is given by IV drip over 21 hours and is extremely effective if given within 8 hours of overdose.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.