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Paracetamol

Also known as: Acetaminophen
Formal name: Paracetamol

At a Glance

Why Get Tested?

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

When to Get Tested?

At least 4 hours after a single overdose, or as soon as possible if more then one overdose has been taken within the last 1 or 2 days

Sample Required?

A blood sample drawn from a vein usually in an arm

The Test Sample

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.

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When is it requested?

Only when paracetamol overdosage is a possibility.

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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.

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Is there anything else I should know?

Taking as few as 10-20 500 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.

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Common Questions

1.  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). It is extremely unlikely that poisoning will happen with this recommended dose and dose interval.

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2.  Is paracetamol overdose dangerous in children?

It is unlikely that liver damage will follow after accidental paracetamol ingestion by a child aged less than 10 years. Serious paracetamol poisoning in children is only likely if the recommended dosage is exceeded repeatedly.

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3.  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.

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.