What Is the THC-COOH Metabolite Drug Test Cutoff?

The THC-COOH metabolite drug test cutoff is 50 ng/mL for a standard urine immunoassay screen and 15 ng/mL for the confirmatory GC-MS or LC-MS/MS test. THC-COOH (11-nor-9-carboxy-THC) is the non-psychoactive breakdown product of THC that labs target, because it stays in the body far longer than the parent drug.

Cannabis Metabolite Test Accuracy Guide

A cutoff is not a measure of impairment. It is the line a lab uses to label a sample negative or positive, and that line shifts with the test type and the lab's contract.

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Standard THC-COOH Cutoffs by Test Type

• Urine screen (immunoassay): 50 ng/mL, the federal standard for DOT and most employers. Instant cups range from 20 ng/mL to 100 ng/mL.
• Urine confirmation (GC-MS or LC-MS/MS): 15 ng/mL.
• Blood: often 1 to 2 ng/mL for THC-COOH. There is no federal blood cutoff.
• Oral fluid: 4 ng/mL screen and 2 ng/mL confirmation under DOT rules, and labs there look for parent THC more than THC-COOH.
• Hair: 0.1 pg/mg for THC-COOH, a much smaller unit of measure than ng/mL.

Why Labs Use Two Cutoffs

The 50 ng/mL screen is a fast, cheap antibody test. It can react to other cannabinoids such as cannabinol or cannabidiol, so a positive screen alone is not proof.

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Any screen above 50 ng/mL goes to a second test that isolates THC-COOH and measures it against the 15 ng/mL line. A sample is reported positive only when the confirmation clears 15 ng/mL.

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This gap explains a common surprise: a sample screens positive at 54 ng/mL and confirms negative at 9 ng/mL.

How Long Does THC-COOH Stay Above the Cutoff?

Detection time depends on how much THC entered the body, how often, and how fast the person metabolizes it. Body fat matters because cannabinoids are stored in fat and released back into blood over time.

• Single use: 1 to 3 days in urine for most people.
• Weekend use: 3 to 7 days.
• Most days of the week: 10 to 21 days.
• Heavy chronic use: 30 days or more, with some cases past 60 days.
• Hair: up to 90 days, since hair grows about 1 cm per month.

These ranges come from population studies, not personal forecasts. Two people with the same habit can test negative on different days.

What Pushes a THC-COOH Level Over or Under the Cutoff?

Factors that raise the number

• High dose and high potency products, including concentrates and edibles.
• Long term frequent use, which builds a body burden that clears in steps.
• Higher body fat, which extends the release of stored cannabinoids.
• Full spectrum CBD oil taken in large amounts, since trace THC can add up.

Factors that lower the number

• Time since last use. This is the main factor.
• Fast metabolism, younger age, and higher muscle mass.
• Lower body fat.
• Water loading, which dilutes urine but often flags the sample as invalid.

Dilution and Adulteration Checks

Labs measure creatinine and specific gravity on every urine sample. Creatinine under 20 mg/dL or specific gravity under 1.003 means the sample is too watery to test, and it gets reported as diluted instead of negative.

Many employers treat a diluted result as a refusal or demand a retest on a supervised collection. Bleach, vinegar, and commercial cleansers tend to get caught by the same panel.

Screen Positive, Confirmation Negative: What Happened?

A low level of THC-COOH that landed between 15 and 50 ng/mL is the common cause. That window shows up at the tail end of clearance, when a person sits close to testing clean.

Other causes include cross reactivity on the immunoassay from other cannabinoids and normal variance between test kits.

The confirmation result is the one that counts for a medical review officer or an employer.

Do CBD Products Cause a THC-COOH Positive?

Isolate CBD holds no THC, so it should not produce THC-COOH. Full spectrum and broad spectrum products can carry small amounts of THC, and heavy doses taken over weeks have produced positives in published case reports.

At the 50 ng/mL screen, a single serving is unlikely to matter. Repeated high doses are where the risk sits.

Common Questions About THC-COOH Cutoffs

Is 50 ng/mL a high cutoff?

It sits in the middle. Some instant tests use 20 ng/mL, which catches use closer to the last dose, and some pre-employment panels use 100 ng/mL, which misses more recent use.

Can a lab report a positive below 15 ng/mL?

No. Federal guidelines set 15 ng/mL as the lowest reportable level for urine confirmation. Levels under that are reported as negative.

Does passing a 50 ng/mL home test mean I will pass a lab test?

Not always. Home strips and lab immunoassays differ in sensitivity, and the lab also runs a confirmation at 15 ng/mL. A faint line at home can still confirm positive.

Can secondhand smoke push me over the cutoff?

Only with hours of exposure in a closed space. Typical secondhand contact does not reach 50 ng/mL in urine.

Do all employers use 50 ng/mL?

No. DOT regulated testing uses 50 ng/mL, but private employers can choose 20 ng/mL or 100 ng/mL based on their policy and the panel they buy.

What This Means for Legal Cannabis Users in the US

Buying cannabis at a licensed shop in your state does not change a lab cutoff. Most employers set their own testing policy, and a positive THC-COOH result can end a job offer even where cannabis is legal.

If you use cannabis and face a test, the numbers above are what decide the result. Clearance time, not the legal status of the product, drives the outcome.