Cocaine Levels in a Hair Follicle Test: Cutoffs, pg/mg Numbers and What Your Result Means

Updated 21 Oct 2026 · By the DrugTestAnswers Editorial Team

If you've seen a number next to cocaine on a hair test report, or you're trying to figure out whether your use would land above the line, you've probably noticed that nobody explains the numbers in plain words. That's what this page does. We'll walk through the units labs use, the cutoffs that decide positive or negative, the extra compounds labs check so they can tell real use from contamination, and why a single number can't tell anyone exactly how much or how often you used. No scare tactics and no sales pitch dressed up as science, just the stuff a friend who reads lab reports for a living would tell you over coffee. We may earn a commission if you buy through links on this page.

The quick version

A cocaine hair result is a measurement of how many picograms of cocaine (and its breakdown products) sit inside each milligram of your hair. A lab screens the sample first, and only if it's above the screening line does it run a second, more exact test. Under most published guidelines, the line for cocaine is 500 picograms per milligram. To call the sample positive, the lab usually also needs to find a metabolite, mostly benzoylecgonine, at a set level and in a set ratio to cocaine, which helps show the drug went through a body rather than just landing on the hair from outside.

Above the line, the exact number matters less than people think. It shifts with hair colour, hair treatments, how close to the scalp the hair was cut and the lab's own method. That's why reputable labs won't turn a single number into a verdict like "heavy user."

What "pg/mg" actually means

Hair results are written as a mass of drug per mass of hair. The two units you'll see are:

• pg/mg, picograms of drug per milligram of hair. A picogram is a trillionth of a gram.
• ng/mg, nanograms per milligram. One nanogram is a thousand picograms, so 0.5 ng/mg is the same as 500 pg/mg.

Some reports and research papers switch between the two, which is why the same cutoff can look like "0.5" in one place and "500" in another. A standard sample is about 100 milligrams of hair, roughly a pencil-width lock cut at the scalp, though labs can work with less.

Screening first, confirmation second

Every hair lab works in two stages. The first is a screen, usually an immunoassay, which is fast and cheap and reacts to cocaine and closely related compounds as a group. If the screen comes in under its cutoff, the sample is reported negative and that's the end of it. If it comes in at or above, the lab moves to confirmation using mass spectrometry (often LC-MS/MS or GC-MS), which measures each compound separately and exactly.

Only the confirmation numbers decide a positive. If the screen flags a sample but confirmation finds cocaine under the line, or finds cocaine without the required metabolites, the result is reported negative. Our guide to screening vs confirmation results covers this two-step process in more detail across all test types.

The published cocaine cutoffs

There isn't one law that sets hair cutoffs for private employers. Labs follow a mix of their own validated limits and published guidance. The two references you'll see most are the Society of Hair Testing, an international scientific group, and the U.S. Department of Health and Human Services, which proposed federal hair testing guidelines in 2020. They line up closely for cocaine:

Individual labs can and do set slightly different limits, so the numbers on your report are the ones that count. You can compare these with urine and oral fluid cutoffs on our cutoff levels table.

Why labs care about benzoylecgonine and the ratio

Cocaine is unusual among drugs because it's often handled as a powder, sits on surfaces and travels on hands, and it sticks well to hair. That means someone can end up with cocaine on the outside of their hair without using it. Labs know this, and it's a big reason the rules look the way they do.

Benzoylecgonine is what the body turns cocaine into. Finding it at a meaningful level, and in a meaningful proportion to cocaine (the 5% ratio, written as BE/COC of 0.05 or more), makes a stronger case that the drug was taken in and carried into the hair from the blood. The catch, which labs openly discuss, is that a small amount of benzoylecgonine can also form outside the body when cocaine sits on hair and breaks down, so the ratio is a strong clue rather than proof. Cocaethylene and norcocaine are harder to explain by contamination, which is why some labs treat them as extra confirmation.

If you're worried about how contamination fits into all this, our page on false positives for cocaine on a hair test goes into the research.

The wash step and what it does to your numbers

Before testing, labs wash the hair, often several times with solvents and buffers, to strip off anything sitting on the surface. Some labs test the wash liquid too. If a large share of the cocaine comes off in the wash, that suggests outside contamination. If most of it stays put inside the hair after washing, it's more likely to have come from inside the body.

This matters for two reasons. First, it's why the number on your report is lower than what was technically on your hair when it was cut. Second, it's why "just shampoo really well before the test" doesn't change much: the lab's own wash already removes what an ordinary shampoo would.

Is there a cocaine levels chart for light, moderate and heavy use?

You'll find charts online that sort cocaine hair levels into neat bands like "light," "moderate" and "heavy." We aren't going to publish one, and here's the honest reason. Research does show a general trend, where people who use more often and in bigger amounts tend to have higher levels. But the spread between individuals is huge. Two people with the same habit can end up with levels many times apart, and one person's numbers can swing from one month of hair to the next.

Some labs and researchers do describe rough ranges for their own data, and expert witnesses sometimes talk about levels being "consistent with" regular use. Those are interpretations made with a lot of context, not a lookup table. If you see a chart that claims a specific number means you used a specific amount, treat it as a guess.

What pushes a cocaine level up or down

Here are the main things that change the number, other than how much was used:

• Hair colour. Cocaine binds to melanin, the pigment in hair. Darker hair tends to hold more of it than blonde or grey hair after the same exposure. This is one of the best-documented effects in hair testing.
• Bleach, dye, perms and relaxers. Strong chemical treatments damage the hair's structure and can lower the measured level, sometimes a lot. They don't lower it reliably or predictably, and they cause their own problems. See our page on hair dye, bleach and hair tests.
• Sun and weathering. Hair that's been exposed to UV and repeated washing for months tends to read lower toward the ends.
• Where on the head the hair came from. Growth rate varies across the scalp, and the back of the crown is the standard spot because it's the most consistent.
• Length of the sample. A longer sample averages over more months. A burst of use in one month gets diluted by clean months on either side.
• The lab's method. Extraction and instruments differ, and so does the exact number one lab gets compared with another.

How the sample length turns into a time window

Scalp hair grows about a centimetre a month, roughly half an inch, though it varies from person to person. A standard sample is about 1.5 inches (3.9 cm) cut right at the scalp, which works out to about the last three months. There's also a lag at the start: hair that formed in the past week or so hasn't grown above the scalp yet, so very recent use usually isn't in the sample.

The cocaine level in a standard sample is an average over that whole stretch. It isn't a timeline. A report that says 1,800 pg/mg doesn't tell you whether that came from steady use all three months or a heavier stretch in one of them.

Segmental testing: when the lab cuts the hair into pieces

Some cases call for more detail, so the lab cuts the hair into segments, often one centimetre each, and tests them separately. That gives a rough month-by-month picture. A pattern of falling levels toward the scalp is consistent with someone cutting back. Rising levels point the other way. Segmental testing is more common in disputes and specialist cases than in routine workplace screening, and it costs more.

Even then, it's approximate. Hair doesn't grow at exactly the same speed for everyone, and not every hair is in its growth phase at the same time, so the edges between months blur. For more on reading a full report, see hair strand test results explained.

Single use vs regular use

This is the question behind most searches for cocaine levels. The short answer is that regular use is very likely to produce levels above the cutoff, and a single use may or may not. Research on controlled doses has found that one dose can show up in hair in some people, especially with dark hair and a larger dose, while in others it stays under the line. Nobody can tell you in advance which group you're in.

If you used once, a long time ago, and your hair has grown out past the standard sample length, that use is likely no longer in the sample. If it was within the last few months, it may be. The practical answer is to stop guessing and check with a home test, which we come back to below.

Crack vs powder on the report

A hair report doesn't say "crack" or "powder." Both are cocaine and both show up as cocaine and benzoylecgonine. When crack is smoked, a small amount of a compound called anhydroecgonine methyl ester forms from heating, and some specialist labs look for it, but standard employment panels don't usually report it. In practice, the route mostly shows up as differences in the overall level, not as a separate line on your report.

Cocaethylene: the alcohol marker

When someone uses cocaine and drinks alcohol around the same time, the liver makes cocaethylene. Its presence in hair is good evidence that both happened together, and because it doesn't form from cocaine sitting on the hair, it's also one of the harder findings to explain away as contamination. If you see it on a report, it tells you the lab found both cocaine use and alcohol use in the same window. For the bigger picture on cocaine and hair tests, including timing and what people try, see our guide to cocaine and hair follicle tests.

What an employer actually sees

Most workplace programs don't hand the employer a page of numbers. A laboratory result goes to a Medical Review Officer, a doctor who checks it, contacts you if it's positive, and asks whether there's a legitimate medical explanation. The employer typically gets a simple "negative," "positive for cocaine" or similar. The pg/mg values stay on the lab report, which you can usually ask for.

That's worth knowing if you're stressing over whether your number is "high." For a routine employment test, a confirmed positive is a positive, whether it's 600 pg/mg or 6,000.

Is there a medical explanation for cocaine in hair?

Very rarely. Cocaine is still used in medicine as a topical anaesthetic, mainly in some nose, sinus and eye procedures. If you had one of those in the months before your test, tell the Medical Review Officer and have the records ready. Other numbing drugs that end in "-caine," such as lidocaine and benzocaine, are different compounds and don't show up as cocaine. Coca tea and coca leaf products, which are legal in some South American countries, can cause positives, though they're not legal to bring into the U.S.

Reading your own report, line by line

If you've got a copy of the lab report, here's what to look for:

1. Specimen type. Confirm it says head hair or body hair. Body hair covers a longer, less precise window.
2. Screening result. Usually "positive" or "negative" with the screening cutoff listed.
3. Confirmation results. Each compound with a measured value in pg/mg or ng/mg and its cutoff.
4. Metabolite ratio. Some reports list the benzoylecgonine-to-cocaine ratio; others just give both values so you can work it out.
5. Chain of custody. The specimen ID should match your custody form, and the seal should have been intact.
6. Segments, if any. Each segment's length and level.

If something looks off, such as the wrong ID, a body hair sample you didn't give, or a level barely over the line with no metabolite listed, you can ask the Medical Review Officer about it, and in many programs you can request a retest of the same sample at another certified lab, usually at your own cost.

Check your own hair before you're tested

The best way to stop guessing about levels is to get a real answer from a lab before your employer does. Home hair follicle kits let you cut a sample yourself, mail it in and get a private result. A negative means you can stop worrying. A positive at least tells you where you stand while you still have time to think. Look for a kit that confirms positives by mass spectrometry, so you're getting the same kind of result a workplace lab would produce. Our best hair follicle drug test kits page compares options.

Can a shampoo lower cocaine levels in hair?

This is where product claims and evidence part ways, so we'll keep it factual. Detox shampoos sold for hair tests, including Old Style Aloe Toxin Rid from TestClear, are marketed as deep-cleaning the hair shaft before a test. TestClear describes Old Style Aloe Toxin Rid as a multi-day cleansing shampoo with its own usage directions; you can read the maker's details on the Old Style Aloe Toxin Rid page at TestClear. What no one has, including the maker, is independent published research showing that it, or any shampoo, reliably brings cocaine levels inside the hair under a lab cutoff.

Cocaine is also a tough case for any cleanser because it binds tightly to melanin deep inside the hair, which is the opposite of what a surface wash reaches. That doesn't mean people don't try it. It means you should go in with realistic expectations and never treat a shampoo as a guarantee. Our Aloe Toxin Rid review and how-to-use guide lays out exactly what the maker claims, what's proven, and the directions TestClear gives.

Harsh home routines and why they backfire

Because chemical treatments can lower measured levels, some people go hard with bleach, multiple dye jobs or routines like Macujo and Jerry G that stack vinegar, acne wash, detergent and detox shampoo. These can cause chemical burns, scalp blisters and hair breakage, especially when repeated over a few days. Never mix bleach with vinegar, acids or household cleaners; that can release toxic gas. If your scalp burns, blisters or weeps, stop and rinse with cool water, and see a doctor if it doesn't settle.

And remember that heavily treated hair can look obviously treated. Collectors notice, and some programs note it on the form or switch to body hair.

What genuinely lowers your number over time

Only one thing reliably does it: time without use. Each month you don't use, a clean centimetre or so of hair grows in at the scalp and the older hair moves further out, eventually beyond the length that's cut for testing. After about three months clean, a standard 1.5 inch head hair sample usually covers only the clean stretch, though growth speeds vary and body hair can hold older use for longer. Our guide on how long it takes to pass a hair follicle test walks through that timeline.

Myths about cocaine levels

• "My level tells them exactly how much I used." It doesn't. It shows a rough trend at best.
• "A level just over 500 means I barely used." Not necessarily. Light hair, treated hair or a longer sample can all pull a regular user's level down toward the line.
• "Shaving my head resets the numbers." Collectors move to body hair, which can cover a longer window. See hair drug tests and shaved heads.
• "Being around people who use will put me over." Contamination is possible, which is exactly why labs wash samples and look for metabolites. It's not usually enough to produce a confirmed positive on its own.
• "Labs round up." Confirmation values are measured and compared against the cutoff as reported. There's no rounding in your favour or against you.

Tests this page doesn't apply to

Don't use anything on this page to try to affect a DOT-regulated test (CDL drivers, rail, transit, pipeline, maritime), FAA aviation testing, federal employee programs, military testing, or court, probation and parole testing. Tampering in those programs can count as a refusal and may be illegal.

Where this information comes from

Cutoffs and interpretation rules come from published Society of Hair Testing consensus guidance and the U.S. Department of Health and Human Services' proposed hair testing guidelines, along with peer-reviewed forensic toxicology research on cocaine incorporation, melanin binding, cosmetic treatments and contamination. Product details come from TestClear's own product page. We don't test products on samples or publish testimonials; see our editorial methodology.

If cocaine use is weighing on you

Worrying about a test is often the moment people realise use has become a bigger deal than they wanted. You don't have to sort that out alone. The SAMHSA National Helpline is free, confidential and open 24/7 at 1-800-662-4357, and it can point you to local support without judgment.

Disclaimer and support

Informational only, not medical or legal advice. Tampering with a drug test may be illegal and can count as a refusal or failed test. The only guaranteed way to pass is abstinence. Free, confidential help is available 24/7 from the SAMHSA National Helpline at 1-800-662-4357. In a crisis, call or text 988.