Saliva Test Cutoff Levels: Federal Limits and What They Mean

A saliva test cutoff level is the concentration, measured in nanograms per milliliter (ng/mL), at which a lab reports a drug as positive. Under federal transportation rules, the initial THC cutoff in oral fluid is 4 ng/mL and the confirmatory cutoff is 2 ng/mL. Other drugs have their own numbers, listed below. Outside federally regulated jobs, there is no single required cutoff, so the number on your test depends on who designed the program.

This guide gives you the federal table, explains how to read it, and shows where private employers, schools and individuals have room to choose.

TL;DR

• Cutoffs are concentration thresholds in ng/mL. Below the line, a sample is reported negative. At or above it, the sample moves on to confirmation.
• The federal table in 49 CFR § 40.91 sets oral fluid cutoffs for DOT-regulated testing: 4 ng/mL for THC on the initial test, 15 ng/mL for cocaine, 30 ng/mL for opioids, 10 ng/mL for PCP and 50 ng/mL for amphetamines.
• Federal numbers apply to safety-sensitive transportation work, not to every employer. Private programs can set their own thresholds.
• A lower cutoff lengthens the detection window. A higher cutoff favors recent use.
• A positive on a screening device is presumptive. A laboratory confirmation is what makes a result defensible.

Table of Contents

• What a cutoff level actually is
• The federal oral fluid cutoff table
• Who must use these numbers, and who does not
• How the cutoff changes the detection window
• Reading a result: what 50 ng/mL really means
• Why collection device and biology matter
• Choosing a cutoff for a private program
• Our perspective: treat the cutoff as a decision you make on purpose
• Where to start with your own testing
• Frequently asked questions
• Sources

What a cutoff level actually is

Every drug test measures something: a parent drug or a metabolite in a sample. Instruments can detect very small amounts, so a program has to decide how much counts. That decision is the cutoff.

Think of it as a bar set at a specific height. A sample that clears the bar is reported positive for that drug. A sample that stays under it is reported negative, even if a trace is physically present. This is why “negative” on a drug test does not mean “zero.” It means “below the threshold this program chose.”

Research on oral fluid describes the distinction between two kinds of cutoffs, and the difference matters:

• Initial (screening) cutoff. The first test, designed to sort samples quickly. Samples at or above it go on for further testing.
• Confirmatory cutoff. A more specific second test, usually run by a laboratory using a different method, that identifies exactly what is present and how much.

In federal oral fluid testing, the confirmatory cutoff is often lower than the screening one. For example, amphetamines are screened at 50 ng/mL and confirmed at 25 ng/mL, as the table below shows. The screen casts a wide net quickly. The confirmation is the precise measurement.

The federal oral fluid cutoff table

The official source is 49 CFR § 40.91, the Department of Transportation rule on oral fluid cutoff concentrations. The DOT’s own copy of the rule carries the same table. All values are in ng/mL.

Two things stand out. First, saliva cutoffs are generally much lower than the numbers people associate with urine testing, because saliva carries drugs at lower concentrations than urine. Second, the table is not fixed forever. The revised Mandatory Guidelines for oral fluid set up a process in which the Department of Health and Human Services publishes the authorized drug panel, including analytes and cutoffs, on an annual basis. Check the current published panel before you build a compliance program around any number you read online, including ours.

If you manage a DOT-regulated workforce, our guide to DOT oral fluid testing and employer action steps walks through what changes for your program. For the broader SAMHSA picture, see SAMHSA cutoffs and a six-step audit-proof checklist.

Who must use these numbers, and who does not

This is the most common misunderstanding about saliva test cutoff levels. The numbers above are mandated for federally regulated programs. 49 CFR Part 40 governs transportation workplace testing: trucking and logistics, aviation, railroads and public transit, among others. Federal agency testing follows the HHS guidelines.

A private employer outside those categories is not bound by that table. The same goes for private high schools, treatment programs, attorneys arranging testing for a case, and individuals testing at home. They can choose a test with a cutoff that is higher, lower or simply different from the federal one.

That freedom is useful, and it has a catch. A result is only as meaningful as the threshold behind it. If one employer tests at the federal THC level and another uses a device with a much higher one, a person could be negative under the second program and positive under the first on the same day.

What this means in practice

• Regulated transportation employer: use federally compliant collection, certified laboratories and the published federal cutoffs. No shortcuts.
• Private employer: decide your goal first (deterrence, post-incident, reasonable suspicion), then choose the cutoff that fits. Write it into your policy.
• Parent, school or family-law matter: know the cutoff printed on the device or lab report, and ask what it was designed to detect.
• Individual: read the package insert. The cutoff is listed for each drug on the device.

How the cutoff changes the detection window

The cutoff and the detection window are linked. A lower cutoff catches smaller amounts, and small amounts persist longer as a drug clears. A higher cutoff only catches larger concentrations, which are typical of more recent use.

Published research on cannabinoids in oral fluid notes that THC can stay detectable for days in chronic users, and that this depends heavily on dose, smoking history and the sensitivity of the cutoff applied. A single, occasional user will usually clear much sooner.

That gives employers a strategic choice:

1. Lower cutoff, longer window. Better for deterrence and for catching patterns of use over time.
2. Higher cutoff, shorter window. Better when the question is whether someone may have used recently, such as after an incident or in a safety-sensitive role on shift.

Neither is “correct.” The right choice follows the program’s purpose. For worked examples with THC specifically, read our breakdown of THC detection in saliva by cutoff and the wider overview of how long THC stays in your system.

Reading a result: what 50 ng/mL really means

People search for “what does a 50 ng/mL cutoff mean” because that number appears on so many device labels. Here is the plain version.

A 50 ng/mL cutoff means the device is set to flag a drug or metabolite only when the concentration reaches 50 ng/mL or more. Anything below is reported negative. A sample at or above it is a non-negative result that should go to confirmation. Remember that the number is not a measure of impairment, and it is not a measure of how much someone used. It is simply the line the test was built around.

In the federal table, 50 ng/mL is the screening cutoff for amphetamines and MDMA/MDA. The confirmatory cutoff for the same drugs is 25 ng/mL. So a single number on a label tells you only half the story. Always ask: is this the screening level or the confirmation level, and for which drug?

Why a positive is not the end of the process

A presumptive positive on a point-of-collection device is a reason to confirm, not a conclusion. Laboratory confirmation uses a more specific method to identify the substance and measure it. In federal programs, a verified non-negative result is then reviewed by a Medical Review Officer (MRO), who considers legitimate explanations.

The MRO step exists for good reasons. For example, CDC guidance notes that selegiline, a Parkinson’s medication, can metabolize into methamphetamine and amphetamine, which can produce a lab positive that has a medical explanation. Anyone taking a prescription should disclose it to the MRO or the testing administrator, not hide it.

If you are an employer, build a pause into your disciplinary process. Do not act on a screening result alone.

Why collection device and biology matter

Cutoffs are not the only variable. Researchers who study oral fluid, including Dayong Lee and Marilyn Huestis, point out in their review of cannabinoids in oral fluid that results are shaped by pharmacokinetics, individual metabolism and even the collection device used. A result is an analytical measurement that must be read against the program’s goals and thresholds, not a simple yes or no.

Practical consequences:

• Collection technique. Follow the instructions about not eating, drinking or smoking before collection. The device’s directions will give the wait time.
• Device differences. Different devices dilute the sample differently, which is one reason lab-reported cutoffs are tied to a specific collection system.
• Drug-specific behavior. Some drugs move into saliva readily, and others are present at lower levels. Research shows that oral fluid concentrations of basic drugs such as amphetamines, cocaine and some opioids tend to be similar to or higher than plasma levels. Detection time for other drugs depends on dose and use pattern. A study of benzodiazepines in patients in detoxification tracked how long diazepam, clonazepam and alprazolam stayed detectable in oral fluid after heavy, repeated intake.

The lesson is consistent: treat cutoffs as design choices, not laws of nature.

Choosing a cutoff for a private program

If your organization is not federally regulated, here is a simple way to decide.

1. Define the purpose. Pre-employment screening, random testing, post-accident, return-to-duty and school athletics all have different goals.
2. Decide the window you need. Do you want to know about use in the past day or two, or longer-term patterns?
3. Consider whether to mirror federal levels. Matching the federal table gives you a recognized benchmark and easier defense if a result is challenged. It also means aligning with certified labs.
4. Choose the right panel. A 5-panel and a 10-panel test are not interchangeable. The panel determines which drugs are tested, and each drug has its own cutoff.
5. Plan confirmation. Decide in advance which lab confirms non-negative screens and at what cutoff.
6. Write it down. Put the panel, cutoffs, collection steps and consequences into a written policy, and have legal counsel review it.

The federal Mandatory Guidelines describe the purpose of standardization as bringing the same scientific and forensic rigor to oral fluid that has long existed for urine. Private programs do not have to follow them, but borrowing their structure is a sound way to stay defensible.

If zero-tolerance THC is your policy, our pages on zero-tolerance THC lab confirmation and zero-tolerance THC test FAQs explain how that approach is typically handled.

Our perspective: treat the cutoff as a decision you make on purpose

We talk to employers, clinics and attorneys every day, and the same pattern shows up. People buy a test, glance at the panel, and never look at the cutoff. Then a result gets challenged and nobody can explain the number.

Here is how we think about it.

Know which world you are in. If you are in DOT-regulated work, the table in 49 CFR Part 40 is your world, and you need certified labs and proper chain of custody. If you are not, you have choices, and choices carry responsibility.

Match the test to the question. A screening device answers “is there a reason to look closer?” A laboratory answers “what exactly is present, and how much?” Different questions, different tools. That is why we work with laboratories that meet SAMHSA, ISO, CLIA and CAP standards, and why we offer custom panels and orders when a standard kit does not fit the need.

Do not skip confirmation. A presumptive result should be treated as a presumptive result. If a decision affects someone’s job, custody case or license, confirm it.

Read the insert. Whether you buy from us or anyone else, find the cutoff for each drug before you rely on the result.

Cutoffs are not trivia. They are the definition of what “positive” means in your program.

— Alan

Where to start with your own testing

If you need a screening device for your workplace or home, you can browse 2 panel and 3 panel drug tests, or the 12 panel at-home cup test for broader coverage. For staffing needs, see our staffing drug tests. When a result must hold up, or you need a specific or custom panel, our lab testing services connect you with certified laboratories. You can also look through all lab tests or start from our homepage to ask about custom orders for employer and federal programs. Orders over $75 ship and return free, and we back orders with a money-back guarantee.

Before you order oral fluid testing for a regulated program, read what to check about HHS-certified labs. For a look at why employers choose saliva in the first place, see oral fluid drug testing: workplace reliability and fast results.

Frequently asked questions

What is the standard cutoff level for a saliva drug test?

There is no single standard for every program. For DOT-regulated testing, the federal table sets 4 ng/mL for THC, 15 ng/mL for cocaine, 30 ng/mL for opioids, 10 ng/mL for PCP and 50 ng/mL for amphetamines at the initial stage. Private programs may use different levels, so check the device or lab report.

What is the federal THC cutoff for saliva?

Under 49 CFR § 40.91, the initial oral fluid cutoff for marijuana (THC) is 4 ng/mL, and the confirmatory cutoff is 2 ng/mL. These apply to DOT-regulated testing. A non-DOT employer is not required to use them.

Are saliva cutoffs the same as urine cutoffs?

No. Saliva generally carries drugs at lower concentrations than urine, so oral fluid cutoffs are set at different, often lower, levels. You cannot compare a saliva number and a urine number directly, and each matrix has its own detection window.

Can a lower cutoff cause more positives?

Yes. A lower cutoff detects smaller concentrations and extends the detection window, so more samples can cross the line. That is why confirmation testing and Medical Review Officer review matter, especially when someone may have a legitimate prescription.

Do cutoff levels change over time?

They can. Under the revised oral fluid guidelines, HHS publishes the authorized drug testing panel, including cutoffs, annually. Always confirm the current panel with the official source before writing or updating a policy.

Sources

• 49 CFR § 40.91, cutoff concentrations for oral fluid drug tests (Cornell LII)
• DOT Rule 49 CFR Part 40 Section 40.91 (U.S. Department of Transportation)
• Mandatory Guidelines for Federal Workplace Drug Testing Programs (Federal Register)
• Current Knowledge on Cannabinoids in Oral Fluid (PMC)
• Detection Times of Diazepam, Clonazepam, and Alprazolam in Oral Fluid (PubMed)
• Expanded Polysubstance Overdose Biosurveillance (CDC Stacks)

Recommended

• U.S. Employers: SAMHSA Cutoffs and a 6 Step Audit Proof Checklist
• 12–30 Hours: THC Detection in Saliva by Cutoff, for Employers and Test
• What Are the Cut-Off Levels for Drug Tests?
• DOT Oral Fluid Testing: 2026 Rules and Employer Action Steps