In order to assess risk of liver damage after over-dosage and to decide on the need for protective, antidotal therapy
Four hours after a single overdose, or as soon as possible after that, and immediately if more than one overdose has been taken within the last 1 or 2 days. It is best to treat an overdose within 8 hours whenever possible.
A blood sample drawn from a vein usually in an arm
The plasma paracetamol concentration is being measured
Normally from a vein in the arm by use of a needle and syringe
The plasma paracetamol concentration is used to establish a diagnosis of paracetamol overdosage and to help decide on the need for treatment.
Only when paracetamol overdosage is a possibility.
The plasma paracetamol concentration at a known time point between 4 and 15 hours after a single overdose has been taken, indicates the likelihood of liver damage developing after 2 or 3 days. This test therefore helps the doctor decide on the need for antidotal treatment to minimise the risk of such damage occurring.
Taking as few as ten to twenty 500 milligram paracetamol tablets at once can cause serious, possibly fatal liver damage 2-4 days afterwards unless antidotal treatment is given within 15 hours. It is likely that there will be no symptoms of poisoning for 24-36 hours after taking the paracetamol even if a potentially fatal dose has been ingested. If paracetamol has been taken above the recommended dose you should seek medical help as soon as possible.
There is increased risk of liver injury with an overdose if persons are malnourished for any reason or alcoholic or if fasting for more than a day.
Adult1g/dose at minimum dosing interval of 4hrs and not to exceed a maximum of 4g in 24 hours
Children 6- 12 years 500mg/dose at minimum dosing interval 4 hours and not to exceed a maximum of 2g in 24 hours
1 -5 years 240mg/dose at minimum dosing interval 4 hours and not to exceed a maximum of 960mg in 24 hours
3 – 12 months 120mg/dose at minimum dosing interval 4 hours and not to exceed a maximum of 480mg in 24 hours
Paracetamol is one of the safest, most effective drugs known if used at the recommended dose (in adults 2 x 500 milligram tablets or capsules taken every 4-6 hours if necessary).
Apart from the Related Tests noted above, there are no other related pages on this site.
The Royal Children's Hospital Melbourne: Paracetamol poisoning clinical guideline
Patient UK: Paracetamol poisoning
Last Review Date: October 27, 2011