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Cannabinoid Hair Screening (Quantitative)

Published: August 9, 2026Updated: August 16, 2026

This test measures the presence of cannabinoids, the active compounds found in cannabis, in your hair. Hair testing can provide information about your exposure to cannabis over a longer period, typically months to years.

Quick summary

["Hair testing helps track past cannabis use and exposure levels over time."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
26764-1
Short code
CANHAIR
Synonyms
Cannabinoids Hair Ql
Category
chemistry
Sample
serum
Container
Foil-wrapped hair specimen envelope or sterile specimen container for hair collection
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
1–99 years
Method
Immunoassay screen with Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) confirmation
CPT
80101 (qualitative screen); 80349 (GC-MS confirmation); G0480 (definitive drug confirmation, if applicable)
SNOMED
314529007 | 386951005
Specimen volume
50-100 mg of hair (approximately 50-100 strands), ideally collected from the posterior vertex region of the scalp, cut close to the scalp
Stability
Stable at room temperature (15-25°C) for up to 2 weeks; refrigerated (2-8°C) for up to 3 months; frozen (-20°C or below) for long-term storage up to 1 year
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
48–168 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test if they suspect long-term exposure to cannabis, especially if symptoms like memory issues, mood changes, or physical dependence are present. Hair testing can also be used in certain legal or workplace settings to assess compliance with substance-use policies.

What Does the Test Involve?

A small sample of your hair is collected, usually from the back of your head. The hair is analyzed to detect cannabinoid compounds, which can remain in your system for an extended period after use.

How Is the Test Performed?

The test uses a specialized laboratory technique to measure the concentration of cannabinoids in your hair. This method helps identify whether cannabinoids were present in your system at some point, even if they are no longer detectable in blood or urine.

What Do the Results Mean?

Positive results indicate past exposure to cannabis, but they do not show when or how recently you used it. The presence of cannabinoids in your hair does not necessarily mean you are currently experiencing withdrawal symptoms or active use.

Reference range

Negative (cutoff: 1 pg/mg for THC; varies by specific cannabinoid analyte). Positive results indicate exposure to cannabinoids within the detection window of hair growth (approximately 90 days).N/A

Specimen: serum

No special patient preparation required. Patients should be advised that chemical treatments (bleaching, perming, dyeing) may affect analyte concentrations in hair. External contamination cannot be fully excluded.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: This test is useful for detecting long-term exposure to cannabis, which may not be captured by urine or blood tests. It can help assess occupational safety, legal compliance, or ongoing health concerns related to substance use.

Short name

Hair Cannabinoid Test

Frequently asked questions

What does a positive result mean?
A positive result means cannabinoids were detected in your hair, suggesting past exposure to cannabis. However, it does not indicate the exact timing or frequency of use.
Can this test detect recent cannabis use?
No, this test primarily detects cannabinoids from months to years ago. For recent use, urine or blood tests are typically used instead.
Is hair testing more accurate than urine or blood tests?
Hair testing provides a broader picture of long-term exposure but may not reflect current use. Both methods have their strengths depending on the clinical context.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy