Most standard hair follicle tests detect cannabis for up to 90 days after the last use. Head hair grows about half an inch per month, so the typical 1.5-inch sample a lab clips reflects roughly a three-month window. The real answer to how long cannabis stays in your hair follicles depends on your hair length, your growth rate, and how heavily you used.
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What Affects How Long Cannabis Stays in Hair Follicles?
Hair length and growth rate set the outer limit, while the lab's cutoff level decides how much metabolite is enough to register as positive. Heavy daily use deposits more THC-COOH per strand than occasional use, so it can stay detectable longer inside the same window.
Key Features
- Detection window: up to 90 days in head hair for most people
- Growth rate: roughly 0.5 inch per month, about 1.5 inches per quarter
- Standard sample: about 1.5 inches of hair or 100 to 120 strands
- Metabolite detected: THC-COOH, a non-psychoactive breakdown product
- Body hair grows slower than scalp hair and can hold metabolites longer
- Recent use may not appear; metabolites need about 7 to 10 days to reach the follicle
- Confirmation testing uses GC-MS or LC-MS/MS after an initial immunoassay screen
How Hair Testing Works
Labs cut a small sample close to the scalp, wash it, then break the strands down so any trapped metabolites release into solution. The extract is screened, and every presumptive positive is confirmed with mass spectrometry. That is why a hair result is reported as a roughly 90-day history rather than a single point in time. Cosmetic treatments such as bleach, dye, or relaxer can strip some metabolite from the shaft, but the effect is inconsistent and nothing is guaranteed.
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Can a Hair Follicle Test Detect Very Recent Use?
Usually not. Metabolites take about a week to reach the follicle, so a test collected a day or two after use may come back negative even when a urine or blood test would not.
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Can You Remove THC From Your Hair Follicles?
No product is proven to clear hair completely. Detox shampoos and treatments may lower metabolite levels slightly, but they cannot be relied on to change a positive result.
Orders placed with Eden Cannabis ship in plain, discreet packaging, and unopened items can be returned under our standard policy within the posted window. If you have questions about a product before buying, our team is happy to help.