In the case of a positive test, another sample of the same hair is usually put through a secondary test that uses techniques called gas chromatography and/or mass spectrometry. These techniques, known as GC/MS and GC/MS/MS (tandem MS), are more accurate, more involved techniques that scan the sample for the “molecular signature” of the target compound.
When you smoke, vape, or eat marijuana, all you’re really doing is facilitating the release of the drug’s active compounds into your bloodstream. Once they’re in your veins, these cannabinoids ride the blood highway to the cannabinoid receptors on the body’s cells, where they bind and exert their effects. Along the way, some of the cannabinoids — metabolites of psychoactive THC are what most tests look for — enter the blood vessels that feed the cells of the scalp. There, at the interface between the vessel and the follicle cells known as the hair papilla, THC jumps the gap, entering the matrix, where actual hair growth occurs. Over the next couple of weeks, the hair from the root sprouts upward, carrying THC past the scalp, where it becomes fair game for testing for the next three months.
The most commonly cited number for the amount of time marijuana can be detected in your hair is 90 days. That time frame is calculated on the basis of how long it takes for hair at the root to grow past the scalp, and it takes into account the part of the hair that drug testers sample.
How long does weed stay in your hair?
The final concentration of the chemical in a sample of hair gives the final verdict. The “confirmatory level” of THCA that Quest Diagnostics uses is 0.1 picograms per milligram of hair. Anything above that pretty much confirms you’ve used marijuana in the past three months.
Once your hair is collected, it’s washed to remove any external contaminants, chopped up, and then digested in a solution meant to break it down into its components — largely the protein keratin, together with any other compounds that make their way into the hair shaft. Usually, that solution is put through an ELISA (enzyme-linked immunosorbent assay) screen, a laboratory procedure that uses specific antibodies to bind the target molecule of choice — in this case, THC. (More specifically, THCA, a direct metabolite of THC.)
How does weed get in my hair, Anyway?
Hair color — that is, hair melanin content — seems to alter the sensitivity of the test, with darker-colored hair being more sensitive to the test, according to a report from the Substance Abuse and Mental Health Services Administration. There has also been some concern about gray hair frequently turning up false positives, though more research is needed to explain why this happens.
The dreaded hair test is one of the most used tests for finding drug users. It’s less invasive and takes less time than urine and blood tests, but it’s also controversial and has been known to cause false positives — even coming in contact with smoke can be enough to mess up your results. But until this issue is sorted out, it’s worth knowing exactly how hair tests work, especially for one of the most common drugs around: weed.
Some good sources of zinc include crab, cashews and oatmeal. To increase iron intake, add spinach, meat and seafood to your diet.
Whether it be from marijuana intake or something else altogether, if you’re dealing with baldness you may be looking for hair loss treatment options.
Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.
There is also some thought that regular marijuana use can trigger the pleasure-seeking portion of your brain. In turn, this could lead you to seek out delicious (but unhealthy) foods while you’re high.
Lifestyle Tweaks to Reduce Hair Loss
Minoxidil is also thought to increase blood flow to your scalp, which can stimulate hair growth.
The final word on weed and hair loss is that there is no final word. There is one study that suggests that THC can build up on hair shafts, damaging the strands.
There are also some studies that seem to suggest that smoking weed could cause certain conditions that may lead to hair loss.
Some shampoos are specifically created to help thicken hair and stimulate hair growth. This thickening shampoo is made with saw palmetto, a natural ingredient believed to work like finasteride to reduce hair loss.
You’ve likely seen biotin gummies on Instagram or in the supplement aisle of your local drugstore. They’ve become a popular product because it’s thought they encourage hair growth.
The science here isn’t exact. But there is some evidence to suggest that people who smoke large amounts of cannabis suffer from slower hair growth and non-genetic baldness.
There are some unhealthy side effects associated with smoking weed. It can disrupt your sleep, limit your cardiovascular capacity, and negatively impact your diet.
The study looked at men and women between the ages of 18 and 60 who regularly smoked weed and discovered that – among young men in particular – there was an increased tendency towards hair loss.