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How Long Do Edibles Stay in Your Hair? Breaking Down the 90-Day Rule
THC from edibles stays in hair up to 90 days. Learn the 7-10 day lag, why hemp products test positive, what body hair means for detection windows.
Written by Sipho Sam
September 30th, 2025
THC from edibles can be detected in hair for up to 90 days after consumption.
There's a 7-10 day delay before those metabolites reach your testable hair.
If your head hair is too short, labs might use body hair instead, extending that detection window beyond 90 days.
Whether you're facing a pre-employment screen, maintaining your CDL, or just trying to understand how hemp products affect testing, you need real answers about what determines detection within this timeframe.
Let's break down exactly what that 90-day rule means for your situation.
Table of Contents
What the 90-day detection window actually means for edibles
Why edibles and smoking look identical to hair tests
The hemp product confusion that catches people off guard
What happens when head hair isn't available for testing
How hair follicle tests work and what counts as positive
Your specific timeline scenarios explained
What actually works versus wishful thinking
How hair testing compares to other drug tests
Understanding workplace policies and testing requirements
Making sense of edibles and hair test timing
What the 90-day detection window actually means for edibles
Labs cut 1.5 inches of hair from your scalp for testing.
Since hair grows approximately 0.5 inches per month, that 1.5-inch sample represents roughly 90 days of your history.
This measurement is based on average human hair growth rates standardized by testing labs across the industry.
Here's where timing gets interesting for your situation.
THC metabolites don't appear in your hair immediately after you consume an edible.
There's a 7-10 day incorporation lag while those metabolites travel through your bloodstream and deposit into growing hair follicles.
If you had an edible last night and get tested tomorrow, that recent use probably won't show up yet.
The metabolites haven't had time to reach the hair that will be cut and tested.
What determines your detection risk isn't the strength of a single edible.
It's how frequently you've consumed THC products within that 90-day lookback period.
Someone who had one 5mg gummy 60 days ago faces different odds than someone who consumed edibles every weekend for two months.
The test doesn't distinguish between a 10mg chocolate and a 100mg brownie from a single consumption event.
It's measuring the accumulation of metabolites over time.
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Why edibles and smoking look identical to hair tests
Hair follicle tests detect THC metabolites that reach your hair through your bloodstream.
Whether you ate a gummy or smoked flower, those metabolites travel the same internal pathway to your hair follicles.
Your liver processes edibles and creates the same detectable markers that smoking produces.
The consumption method doesn't matter once those metabolites circulate in your blood.
One person might eat a 10mg gummy every Friday night for a month.
Another person smokes occasionally on weekends during that same period.
The hair test sees similar patterns of metabolite deposits, not the original consumption method.
This is why "but I only ate edibles, I didn't smoke" won't change your test results.
The test doesn't look for smoke residue or external contamination.
It detects internal metabolites that are incorporated into your hair as it grows.
Regular edible consumption can actually lead to higher metabolite accumulation than occasional smoking.
Edibles often contain precise THC amounts, and users might consume them more consistently.
For beginners wondering about edibles, understanding detection windows becomes crucial for informed decisions.
The hemp product confusion that catches people off guard
Standard drug tests detect THC metabolites regardless of whether they came from hemp gummies, Delta-9, or any other THC variant.
The test doesn't differentiate between "federally legal" hemp products and traditional cannabis.
All THC creates the same metabolites that trigger positive results.
This reality catches people off guard who thought they had found a loophole with hemp-derived products.
"But it's legal in my state," or "I bought it at a regular store," doesn't matter to the test.
The metabolites from that legal Delta-9 gummy look identical to metabolites from any other THC source.
Even CBD products can cause problems if they contain trace amounts of THC.
Regular use of full-spectrum CBD products might accumulate enough THC metabolites to trigger a positive result.
The testing equipment measures metabolites, not legal classifications.
Your employer's drug policy probably doesn't distinguish between hemp and marijuana sources either.
A positive is a positive, regardless of where the THC originated.
Understanding third-party testing and lab results can help you verify THC content in products.
What happens when head hair isn't available for testing
If your head hair is shorter than 0.5 inches, labs need an alternative sample source.
They'll typically turn to body hair from your arms, legs, chest, or underarms.
This is where things get more complicated for detection windows.
Body hair grows differently than head hair.
It has a longer growth cycle and can potentially reflect drug use from further back than 90 days.
Some body hair might capture metabolites from six months ago or even longer.
Shaving your head doesn't let you avoid the test.
It just shifts the collection site and potentially extends the detection window.
Labs are prepared for this scenario and have protocols for body hair collection.
The amount of body hair needed is typically more than head hair since it grows slower.
Labs might need hair from multiple body sites to get enough for testing.
If you have no collectible hair anywhere, some employers might require alternative testing methods.
Most will wait for hair to grow or find some body hair to test.
How hair follicle tests work and what counts as positive
The standard threshold for a positive THC result is 0.1 nanograms per milligram of hair.
This incredibly small amount means the test is highly sensitive to THC metabolite presence.
During collection, a trained technician cuts hair as close to the scalp as possible.
They need about 100 strands, roughly the thickness of a pencil.
The sample gets sealed, labeled, and sent to a laboratory under strict chain-of-custody procedures.
At the lab, technicians wash the hair to remove external contaminants.
This is why secondhand smoke or being around cannabis users won't cause a positive result.
The test specifically looks for metabolites inside the hair shaft, not surface contamination.
The hair gets dissolved in solvents to release the trapped metabolites.
Sophisticated equipment then measures the exact concentration of THC metabolites present.
If the concentration exceeds 0.1 ng/mg, the result is positive.
There's typically a confirmation test using even more precise methods to verify any positive results.
This two-step process makes false positives from laboratory errors extremely rare.
Your specific timeline scenarios explained
Let's map out three common scenarios people face with hair testing.
Scenario 1: Single small edible 40-60 days ago
Detection probability falls into the lower confidence category.
A single, small THC amount from 40-60 days ago falls within the 90-day window but represents minimal frequency.
The key factor here is that it was truly a one-time event with no other THC consumption.
Some people in this situation pass, others don't, depending on individual metabolism and the specific lab's sensitivity.
Scenario 2: Multiple edibles across two months
Detection probability rises to the higher confidence category.
Regular consumption, even if it's just weekends, creates a pattern of metabolite deposits in your hair.
Two 100mg edibles per week for two months will likely produce a positive result.
The frequency of use matters more than the total THC amount consumed.
Scenario 3: Edible yesterday, test next week
Detection probability remains in the lower confidence category due to the incorporation lag.
Remember that 7-10 day lag before metabolites reach testable hair?
If you consumed an edible yesterday and test within the next week, those metabolites probably haven't reached your testable hair yet.
Any consumption from 10-90 days ago would still be detectable though.
These scenarios show general patterns, not guaranteed outcomes.
Individual factors like hair color, thickness, and growth rate can affect results.
What actually works versus wishful thinking
Time without THC consumption is the only reliable way to clear metabolites from your hair.
Once those metabolites are embedded in the hair shaft, they're there until that hair is cut off or falls out naturally.
Detox shampoos and bleaching treatments flood online forums with success stories.
The reality is these methods show inconsistent results at best.
THC metabolites are chemically bound inside the hair shaft, not sitting on the surface.
Special shampoos can't penetrate deep enough to remove embedded metabolites reliably.
Bleaching might affect hair structure but labs can often still detect metabolites.
Labs might reject severely damaged samples or detect the tampering attempt.
Hydration and exercise don't meaningfully impact hair test results either.
Unlike urine tests where dilution might help, hair tests measure historical deposits that water and exercise can't flush out.
Cutting your hair short doesn't help because labs just take the newest growth closest to your scalp.
The only strategy that consistently works is allowing enough time to pass.
New, clean hair needs to grow while you abstain from THC consumption.
For those wondering why edibles affect them differently, metabolism plays a role in processing but not in hair test detection.
How hair testing compares to other drug tests
Blood tests detect THC for the shortest window, typically just hours to a few days after use.
They're looking for active THC in your bloodstream, which clears quickly.
Saliva tests extend slightly longer, usually catching THC use within 24-72 hours.
These are becoming more popular for roadside testing and recent use detection.
Urine tests vary dramatically based on frequency of use.
Occasional users might test clean after a few days, while regular users can test positive for 30 days or more.
Hair tests provide the longest detection window at up to 90 days.
This is why employers in safety-sensitive industries prefer them.
They want to see patterns of use, not just recent consumption.
Hair testing is also the hardest to manipulate or alter.
While people attempt various methods with urine tests, hair tests offer fewer avenues for tampering.
Each test serves different purposes in employment and legal contexts.
Pre-employment screening often uses hair tests, while reasonable suspicion testing might use saliva or urine.
For those curious about how long edibles last in terms of shelf life rather than detection, that's an entirely different timeline.
Understanding workplace policies and testing requirements
Safety-sensitive industries like transportation, healthcare, and energy commonly require hair testing.
Department of Transportation regulations have strict testing requirements for CDL holders.
These industries prioritize hair testing because it reveals patterns rather than single incidents.
Employer policies can enforce drug testing regardless of state cannabis laws.
Even in states with legal recreational cannabis, employers can maintain zero-tolerance policies.
Federal contractors and positions requiring security clearances face additional restrictions.
The disconnect between state legalization and workplace policies creates confusion.
Many people assume legal hemp products or state-legal cannabis won't affect employment.
Most employer policies don't distinguish between THC sources.
Mood cannot provide legal or medical advice about drug testing.
We're providing educational information to help you understand how testing works.
For those interested in the broader cannabis industry careers, understanding testing policies remains crucial.
For those not subject to testing who want to explore hemp-derived options, Mood offers a variety of federally compliant products.
Always understand your workplace policies before making any consumption decisions.
Making sense of edibles and hair test timing
The 90-day detection window for edibles in hair tests is real, but it's not the whole story.
That 1.5-inch hair sample does represent roughly three months of your history.
The 7-10 day incorporation lag means very recent use might not show up.
Body hair testing can extend detection beyond that standard 90-day window.
Frequency of use within that timeframe matters more than the strength of individual edibles.
Multiple small THC amounts create more risk than a single larger consumption.
All THC sources, whether from cannabis edibles, fast-acting gummies, or traditional products, test the same.
The metabolites don't carry labels saying where they came from.
Understanding these realities helps you make informed decisions based on your specific situation.
You can calculate your risk based on when you last consumed it, how frequently you used it, and what type of testing you're facing.
If you've used it within the detection window, there is no magic solution or guaranteed method of passing.
Time and abstinence remain the only reliable approaches to clearing THC metabolites from your hair.
Whether you're navigating employment requirements or simply seeking education about how testing works, knowledge of these timeframes and factors empowers better decision-making.
The gap between hemp product legality and testing realities isn't going away soon.
Until testing methods evolve or policies change, understanding how hair tests work remains crucial for anyone using THC products in any form.
