Cannabinoid screening in hair (qualitative)
This test detects the presence of cannabinoids, the active compounds found in cannabis, in your hair over a long period.
["Hair tests can show drug use from months to years prior."]
Key facts at a glance
- LOINC
- 109681-7
- Short code
- CANH
- Synonyms
- Cannabinoids Msmt Hair
- Category
- chemistry
- Sample
- serum
- Container
- Sterile screw-cap specimen container or foil-wrapped hair collection envelope; labeled with patient ID, collection date, and site of hair collection
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 1–99 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or Gas Chromatography-Mass Spectrometry (GC-MS) following hair decontamination, digestion, and extraction procedures
- CPT
- 80307
- SNOMED
- 271270009
- Specimen volume
- 50-100 mg of hair (approximately 100-200 strands); minimum length 1-2 cm proximal to scalp, ideally 3-6 cm segment
- 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
- 72–168 hours
- Order
- routine
What Does This Test Measure?
Hair cannabinoid testing analyzes trace amounts of cannabinoids (like THC or CBD) trapped in your hair follicles. Hair grows about 0.5 inches per month, so results reflect drug exposure over time, often spanning several months. This method is useful for detecting long-term use that other tests (like urine) may miss.
Why Might You Need This Test?
Hair cannabinoid screening is commonly used in employment settings, legal cases, or when other drug tests (like urine) show inconsistent results. It can also help track chronic use or monitor treatment adherence in medical cases.
How Is the Sample Collected?
A small amount of hair (usually 1–2 inches) is collected from the scalp. No special preparation is needed, but avoid cutting or styling your hair before the test.
What Are the Possible Results?
Results are qualitative (positive or negative) rather than quantitative. A positive result means cannabinoids were detected in your hair, suggesting past use. A negative result means none were found in the tested sample.
Reference range
Negative (cutoff: <1 pg/mg for THC-COOH). Detection window approximately 7 days to 90 days or longer depending on hair length (1 cm ≈ 1 month). Results reported as positive or negative based on laboratory-defined cutoffs.N/A
No fasting required. Patient should refrain from chemical hair treatments (bleaching, perming, dyeing) for at least 1-2 weeks prior to collection if possible. Avoid scalp exposure to topical products containing cannabinoids. Patient consent and chain of custody documentation required for forensic or workplace testing.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Hair cannabinoid tests provide a broader timeline of drug exposure compared to urine or blood tests. They’re less affected by recent use or metabolism but may not detect acute intoxication. Results can be used for employment screening, legal purposes, or assessing long-term substance use patterns.
Short name
Hair Cannabinoid Test (Screen)
Frequently asked questions
Why would someone need a hair cannabinoid test?
What does a positive result mean?
How long does it take to get results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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