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Acetaminophen Level

Toxicology

APAPParacetamolTylenol

Review status

Currently under review

Pending specialist review and validation.

What it shows

This test measures the amount of acetaminophen (also known as paracetamol) in your blood. It is most often used when a recent ingestion is suspected, to check for potential poisoning, or to guide care after an accidental or intentional overdose. The level helps your care team understand how much medicine is in your system at a given time.

Your sample is usually taken at a specific time after ingestion because timing affects how the result is interpreted. In some situations, more than one level may be checked to see how the concentration is changing and to support decisions about treatment.

Why it matters

Acetaminophen is widely used for pain and fever, but too much can injure the liver. A timely blood level helps your clinician decide on treatment to protect your liver, including whether an antidote is needed and how long therapy should continue. Results are often considered alongside your symptoms, other medicines you may have taken, and liver blood tests.

Your clinician may order this test if you may have taken more than recommended, if the timing of ingestion is unclear, or if you have risk factors that could increase harm. Early testing and follow‑up can reduce complications and guide safe care.

Understanding your results

Your result is interpreted together with the time since ingestion, your symptoms, and other clinical information. In many cases, clinicians use a standardized chart to assess risk and the need for an antidote. If the timing is uncertain, or if you took an extended‑release product or other medicines that slow absorption, repeat levels may be needed before decisions are final.

A result that suggests risk usually leads to starting or continuing treatment, monitoring liver tests, and supportive care. A low result with clear timing may mean no antidote is needed, but your care team will advise you about observation and follow‑up. Avoid taking more acetaminophen until you receive instructions, and seek urgent care if you develop worsening nausea, vomiting, abdominal pain, confusion, or yellowing of the skin or eyes.

Reference ranges

66120 umol/L
All sexes
0 days – 18 years
66135 umol/L
All sexes
18 years – 150 years

Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.

Factors that could impact Acetaminophen Level

  • Timing of the blood draw

    Levels are interpreted in relation to when the medicine was taken. A sample that is drawn too early or too late may not reflect the true risk and can require repeat testing.

  • Extended‑release or co‑ingestants

    Extended‑release products and medicines like opioids or anticholinergics can delay absorption, causing the level to rise later than expected and changing how results are interpreted.

  • Activated charcoal or antidote therapy

    Activated charcoal can reduce absorption when given soon after ingestion. Antidote therapy is guided by levels and timing, and may continue even if levels fall, based on overall risk.

  • Alcohol use and liver health

    Chronic alcohol use, malnutrition, or existing liver disease can increase vulnerability to injury. Your clinician will consider these factors when interpreting results and planning care.

  • Drug interactions and enzyme inducers

    Some medicines can affect acetaminophen metabolism, potentially increasing toxic byproducts. Tell your care team about all prescription, over‑the‑counter, and herbal products you use.

  • Children, pregnancy, and older adults

    Special populations may absorb and clear the drug differently. Clinicians may adjust timing of tests, the need for repeat levels, and treatment plans to match individual circumstances.

2026

References

  1. McGill University Health Centre. (2015, July 02). Acetaminophen (Task CD 687315). Laboratory reference ranges.
  2. Chiew, A. L., Isbister, G. K., Duffull, S. B., & Buckley, N. A. (2020). Evidence-based update for paracetamol poisoning in Australia and New Zealand. Medical Journal of Australia, 212(4), 175–183.
  3. Hodgman, M. J., & Garrard, A. R. (2012). A review of acetaminophen poisoning. Critical Care Clinics, 28(4), 499–516.