Acetaminophen Level Test: Purpose, Risks & Results

What is an acetaminophen level test?

An acetaminophen level test is a blood test. It measures the amount of acetaminophen in the blood. Healthcare providers perform this test on babies, children and adults. It helps your provider diagnose acetaminophen poisoning.

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Acetaminophen is a very common over-the-counter pain-relief medication. It’s a safe drug when you take the proper dose and avoid taking it for too long. High doses of acetaminophen can lead to liver damage and death. An acetaminophen overdose is an emergency. If you think you or your child took too much acetaminophen, seek medical help right away.

Your provider (or your child’s provider) might recommend an acetaminophen level blood test if they suspect an overdose. An acetaminophen overdose can happen accidentally or on purpose. An acetaminophen level test gives your provider important information about your health. It also helps them plan treatment.

What is acetaminophen?

The brand name for acetaminophen is Tylenol®. Outside the United States, most people call acetaminophen paracetamol. This medication comes in liquid, chewable, capsule or pill form. It relieves pain and reduces fever.

Your liver processes acetaminophen (and other medications) by filtering out toxins. If you take too much acetaminophen or you take the drug for too long, your liver isn’t able to filter the toxins properly. The toxins build up, causing life-threatening liver disease and liver damage.

Many common over-the-counter (OTC) and prescription medications — especially cold and cough medicines — include acetaminophen. That’s why it’s so important to read labels to avoid taking too much accidentally.

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What is the correct dose of acetaminophen?

Generally, adults shouldn’t take more than 4,000 milligrams (mg) of acetaminophen in 24 hours. You shouldn’t take acetaminophen for longer than 10 days without talking to your provider.

The correct dose for children and adolescents depends on several factors. These include the child’s age, weight and whether the medicine comes in a liquid or solid form. Ask your child’s provider about the proper dose for your child. Remember that the dose will change as your child grows.

When is an acetaminophen level test performed?

Your provider may recommend an acetaminophen level test if you or your child has symptoms of an acetaminophen overdose. Symptoms of an overdose can appear about two hours after taking the medication. But you might not have any symptoms for up to 24 hours. Signs of acetaminophen toxicity in children and adolescents are the same as they are in adults. They include:

• Abdominal pain or cramping.
• Diarrhea, nausea and vomiting and loss of appetite.
• Difficulty breathing and shortness of breath (dyspnea).
• Excessive sweating (hyperhidrosis).
• Fatigue or sleepiness.
• Irritability, confusion or delirium.
• Loss of consciousness (fainting).
• Pain in the right abdomen under the ribs.
• Urine changes, including dark urine, blood in urine (hematuria) or decreased amount of urine.
• Vision changes, such as blurry vision.
• Yellow skin or eyes, which are signs of jaundice.