At a glance

Also known as

Acetaminophen

Why get tested?

In order to assess risk of liver damage after over-dosage and to decide on the need for protective, antidotal therapy

When to get tested?

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.

Sample required?

A blood sample drawn from a vein usually in an arm

What is being tested?

The plasma paracetamol concentration is being measured

How is the sample collected for testing?

Normally from a vein in the arm by use of a needle and syringe

The Test

How is it used?

The plasma paracetamol concentration is used to establish a diagnosis of paracetamol overdosage and to help decide on the need for treatment.

When is it requested?

Only when paracetamol overdosage is a possibility.

What does the test result mean?

Looking for reference ranges?

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.

Is there anything else I should know?

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.

Common Questions

What is the recommended maximum doses of paracetamol?

Adult
1g/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

Is paracetamol dangerous if used appropriately?

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).

Can paracetamol poisoning be treated at home?

No, if paracetamol poisoning is suspected, the plasma paracetamol concentration must be measured in hospital as soon as possible and treatment decided accordingly.

Last Review Date: October 27, 2011