How to Pass a PEth Test Illustration

How to Pass a PEth Test: Tips and Strategies (2024)

by | Updated: Dec 23, 2023

In recent years, the PEth (Phosphatidylethanol) test has gained significant attention as an effective means of detecting alcohol consumption, even in cases of moderate drinking.

As a result, many individuals now face the challenge of passing this test for various reasons, including employment or legal requirements.

In this article, we will explore the science behind the PEth test, how it measures alcohol use, and offer practical tips and strategies to help you successfully pass it.

Armed with a clear understanding of the PEth test and a solid plan of action, you can approach this situation with confidence and clarity.

What is a PEth Test?

A PEth test, or phosphatidylethanol test, is a highly sensitive and specific laboratory analysis used to detect recent alcohol consumption. This advanced biomarker test measures the levels of phosphatidylethanol, a unique compound formed in the presence of ethanol, in the blood.

Unlike other alcohol biomarkers, such as blood alcohol concentration (BAC) and ethyl glucuronide (EtG), PEth offers a more extended detection window and is less susceptible to false-positive results.

It has emerged as a preferred tool for assessing alcohol intake in various settings, including workplace testing, legal proceedings, substance abuse treatment programs, and medical evaluations.

PEth testing provides a reliable and accurate snapshot of an individual’s alcohol consumption patterns, ranging from moderate to heavy drinking. It can detect usage up to three to four weeks prior to the test.

How to Pass a PEth Test Blood Sample

How is a PEth Test Performed?

A PEth test is performed by collecting a small blood sample from the individual being tested. This sample can be obtained through a standard venipuncture procedure or via a dried blood spot (DBS) method, which involves pricking the finger and collecting a few drops of blood on a specialized card.

Once the blood sample is collected, it is sent to a laboratory for analysis.

The lab technicians use sophisticated techniques, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), to accurately measure the levels of phosphatidylethanol present in the blood.

The results are then reported in nanograms per milliliter (ng/mL), providing a quantitative measurement of alcohol consumption over the detection window.

It is important to note that the PEth test is not instantaneous, and the turnaround time for results can vary depending on the lab’s workload and the specific method used. Typically, it takes anywhere from a few days to a week for the results to be available.

What do the Results Mean?

Interpreting the results of a PEth test involves understanding the reported levels of phosphatidylethanol in the blood sample.

These levels, expressed in nanograms per milliliter (ng/mL), provide insight into the individual’s alcohol consumption patterns during the detection window, which can extend up to three to four weeks prior to the test.

Generally, a higher PEth concentration indicates more frequent or heavy alcohol use, while a lower concentration suggests moderate or occasional consumption.

It is essential to note that different laboratories may have varying cutoff levels to classify a positive or negative result. However, a common threshold for a positive PEth test is around 20 ng/mL, which implies significant alcohol consumption.

Some labs may also provide a reference range to help contextualize the results further.

Keep in mind that while PEth tests are highly accurate, factors like certain medications, pre-existing medical conditions, or lab-related issues could potentially lead to false-positive or false-negative results.

Note: It is always recommended to consult with a medical professional or a specialist to better understand the implications of the test results in your specific situation.

How to Pass a PEth Test

Passing a PEth test involves taking measures to ensure that your blood levels of phosphatidylethanol remain below the detection threshold, typically around 20 ng/mL.

Here are some tips to help you pass a PEth test:

Abstain From Alcohol

The most effective and straightforward way to pass a PEth test is to abstain from alcohol consumption for an extended period before the test.

Since PEth has a detection window of up to three to four weeks, it is advisable to avoid alcohol for at least a month to ensure your blood levels fall below the threshold.

Stay Hydrated

Drinking plenty of water can help your body metabolize and eliminate alcohol more efficiently. While hydration does not directly affect PEth levels, it promotes overall health and supports the liver in processing alcohol-related substances.

Maintain a Healthy Diet

Eating a well-balanced diet that includes nutrient-dense fruits, vegetables, lean proteins, and whole grains can help support your body’s natural detoxification processes.

A healthy diet aids the liver in breaking down and eliminating alcohol-related substances, thereby indirectly contributing to lower PEth levels.

Exercise Regularly

Engaging in regular physical activity can enhance your overall health and support your body’s ability to process and eliminate alcohol.

Exercise can also help in reducing stress, which might otherwise lead to alcohol consumption as a coping mechanism.

Be Cautious With Medications and Supplements

Some medications or supplements might contain small amounts of alcohol or could potentially interfere with the PEth test results. Consult with your healthcare provider to ensure that your current medications or supplements will not adversely affect your test outcome.

Plan Ahead

If you are aware of a forthcoming PEth test, make a conscious effort to abstain from alcohol and focus on maintaining a healthy lifestyle well ahead of the test date.

Planning ahead gives your body ample time to metabolize and eliminate any remaining phosphatidylethanol from your system.

Remember: The key to passing a PEth test is to abstain from alcohol and maintain a healthy lifestyle that supports your body’s natural detoxification processes. Always consult with a healthcare professional for personalized guidance and support when preparing for a PEth test.

What are the Risks of a PEth Test?

While PEth tests are generally considered safe and noninvasive, there are some potential risks associated with the blood collection process.

For individuals undergoing a venipuncture procedure, the risks are minimal and might include pain, bruising, or swelling at the puncture site. In rare cases, an infection or excessive bleeding may occur.

However, these risks are significantly lower when using the dried blood spot (DBS) method, which requires only a finger prick to collect a small blood sample.

The primary risk associated with a PEth test lies in the interpretation and consequences of the results. As with any diagnostic test, there is a possibility of false-positive or false-negative outcomes due to lab-related issues, certain medications, or pre-existing medical conditions.

Such inaccurate results can potentially lead to undeserved legal, professional, or social repercussions for the individual being tested.

Therefore, it is essential to consult with a medical professional or a specialist when interpreting PEth test results and consider the potential impact of any confounding factors on the test’s accuracy.


How far Back Does a PEth Test go?

A PEth test can detect alcohol consumption for up to three to four weeks prior to the test. The detection window may vary depending on factors such as the individual’s metabolism, the frequency and amount of alcohol consumed, and overall health.

Why is a PEth Test Used?

A PEth test is used because it provides a highly sensitive and specific measure of recent alcohol consumption.

It is a preferred method in various settings due to its extended detection window and reduced susceptibility to false-positive results compared to other alcohol biomarkers.

PEth tests are commonly used in workplace testing, legal proceedings, substance abuse treatment programs, and medical evaluations to assess an individual’s alcohol consumption patterns.

How Long Does Alcohol Stay in Your System?

The length of time that alcohol stays in your system depends on the specific test being used and various individual factors.

Generally, alcohol can be detected in blood for up to 12–24 hours, urine for 12–72 hours, and saliva for 12–24 hours.

However, certain alcohol metabolites, such as ethyl glucuronide (EtG), can be detected in urine for up to 3–4 days, and phosphatidylethanol (PEth) in blood for up to 3–4 weeks.

What Happens if I Fail a PEth Test?

If you fail a PEth test, the consequences will depend on the context in which the test was administered. In a workplace setting, a failed test may result in disciplinary action, dismissal, or mandatory participation in an alcohol treatment program.

In legal proceedings, a positive result could impact custody battles, probation, or court-ordered treatment. In a medical context, a failed test may lead to a revised treatment plan or referral to a substance abuse specialist.

It is essential to consult with a legal or medical professional to understand the specific implications of a failed PEth test in your situation.

How Much Does a PEth Test Cost?

The cost of a PEth test can vary depending on factors such as the laboratory conducting the test, the method used for blood collection, and any additional services or fees.

Generally, the price of a PEth test ranges from $100 to $300. It is essential to check with the specific laboratory or testing service provider to get an accurate estimate of the cost.

Can a PEth Test Detect Occasional Drinking?

A PEth test is capable of detecting occasional alcohol consumption, but its sensitivity depends on factors such as the amount and frequency of drinking, as well as individual metabolic rates.

While the test is primarily designed to identify moderate to heavy alcohol consumption, occasional drinking may still lead to detectable levels of PEth, especially if the alcohol intake was relatively recent or consumed in larger quantities.

What can Cause a False Positive on a PEth Test?

False positives on a PEth test are relatively rare due to the test’s high specificity; however, certain factors could potentially lead to inaccurate results.

Cross-reactivity with other substances, such as medications or supplements containing small amounts of alcohol or chemically similar compounds, may interfere with the test results.

Pre-existing medical conditions like liver diseases, lipid metabolism disorders, or autoimmune diseases could also affect PEth levels or cause interference in the test. Additionally, lab-related issues, such as errors in sample handling, storage, or analysis, can contribute to inaccurate outcomes.

In rare cases, environmental contamination from exposure to certain chemicals or alcohol-containing products, like hand sanitizers, may impact the test results.

Final Thoughts

Successfully passing a PEth test involves a combination of informed preparation and commitment to a healthy lifestyle.

By abstaining from alcohol well ahead of the test, staying hydrated, maintaining a nutritious diet, exercising regularly, and consulting with a healthcare professional about medications and supplements, individuals can effectively reduce the chances of a positive result.

While the PEth test is highly accurate and its false-positive rate is low, it is essential to be aware of any potential confounding factors and seek expert advice when interpreting test outcomes.

Ultimately, understanding the science behind PEth testing and adopting the right strategies will empower individuals to approach this assessment with confidence and improve their odds of success.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.


  • Schröck A, Thierauf-Emberger A, Schürch S, Weinmann W. Phosphatidylethanol (PEth) detected in blood for 3 to 12 days after single consumption of alcohol-a drinking study with 16 volunteers. Int J Legal Med. 2017.
  • Helander A, Zheng Y: Molecular species of the alcohol biomarker phosphatidyethanol in human blood measured by LC-MS. Clin Chem. 2009.
  • Ulwelling W, Smith K: The PEth blood test in the security environment: What it is; why it is important; and interpretative guidelines. J Forensic Sci. 2018.

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