Hair tests have gained popularity in drug testing for providing a longer detection window than urine or blood tests. This is particularly relevant for infrequent smokers who may be concerned about the traceability of THC (tetrahydrocannabinol), the psychoactive component of cannabis, in their hair. This article delves into the intricacies of THC levels in hair tests, exploring what is considered high and addressing common questions about detection thresholds.

Understanding Hair Testing for THC

Hair testing is a method that analyzes hair follicles for the presence of drugs and their metabolites. When an individual consumes cannabis, THC and its metabolites enter the bloodstream and are eventually deposited in hair follicles as hair grows. As a result, a hair test can provide a historical record of drug use over an extended period.

THC Metabolites in Hair: What to Look For

To understand what is considered a high THC level in a hair test, it’s essential to know what metabolites are typically measured. THC is metabolized in the body to form various compounds, with THC-COOH (carboxy-THC) being the primary metabolite targeted in drug tests. Drug testing laboratories often use a cutoff level, measured in picograms per milligram (pg/mg), to determine whether a sample is positive for drug use.

What Is 1 Pg/Mg?

One picogram per milligram (1 pg/mg) is a measurement unit used to express the concentration of a substance in a given sample, including THC testing in hair. Specifically, 1 pg/mg represents the amount of THC-COOH (the primary metabolite of THC) present per one milligram of hair. This unit is tiny; a picogram is one trillionth of a gram. It signifies a susceptible measurement used in drug testing to detect even trace amounts of THC metabolites in hair samples. Understanding this unit, and mainly how much is 1 pg mg, is crucial for interpreting the results of a hair test and comprehending the precision with which testing facilities can identify and quantify THC levels in hair.

Detection Thresholds for Infrequent Smokers

Individuals who use cannabis infrequently may question, will one hit of weed show up on a hair test. While the detection window for hair tests is longer than that of other methods, it 

has limitations. Experts generally agree that a single exposure, such as one puff or hit, is less likely to produce a positive result in an infrequent smoker hair test.

The concern about will one puff of weed be detected in hair is valid, as the sensitivity of hair tests can vary between individuals due to factors such as hair color, metabolism, and cosmetic treatments. For example, blonde hair retains fewer drug metabolites than darker hair. Additionally, various external factors, such as hair treatments and exposure to environmental contaminants, may impact the accuracy of test results. Thus, the reliability of hair tests for infrequent users is influenced by many factors.

Delta-9 Hair Follicle: Unraveling the Terminology

The term “delta-9” is closely linked to THC, the primary psychoactive compound in cannabis. In the context of hair follicle testing, “delta-9” denotes explicitly the isomer responsible for cannabis’s psychoactive effects. This isomer, delta-9-THC, is a critical focus in drug testing to assess cannabis use. Hair follicle tests aim to detect THC metabolites, including delta-9-THC, within the hair shaft, providing a historical record of cannabis exposure. By identifying these metabolites, particularly delta-9-THC, in hair follicles, these tests offer insights into an individual’s past cannabis use, crucial for scenarios requiring a comprehensive overview of drug history.

Will 2 Hits of Weed Show in a Hair Test?

For individuals who have consumed cannabis more than once but still consider themselves infrequent users, the question of whether two hits of weed will show up in a hair test is pertinent. The answer depends on various factors, including the time elapsed since the last use, individual metabolism, and the sensitivity of the testing method. In general, though, occasional or infrequent use is less likely to result in high THC levels in a hair test.

Determining a High THC Level in Hair

The interpretation of what is considered a high THC level in a hair test depends on the cutoff values set by the testing facility. Commonly, a cutoff value of 1 picogram per milligram (pg/mg) is used in hair testing for THC. If the concentration of THC metabolites in hair, specifically THC-COOH, exceeds one picogram per milligram of hair, the test is generally considered positive.

It’s important to note that cutoff values can vary among different laboratories and testing protocols. Some testing facilities may use slightly different thresholds. Therefore, individuals undergoing hair testing should be aware of the specific cutoff values employed by the analysis facility.

Understanding these cutoff values is crucial for individuals to interpret their hair test results accurately. Suppose the concentration of THC metabolite in the hair exceeds the established cutoff. In that case, it may be indicative of recent or historical cannabis use, depending on the detection window of hair tests.

How Long Does Weed Stay In Hair for Infrequent Users?

The duration that weed stays in the hair for infrequent users can vary based on several factors, including individual characteristics and testing methodologies. Unlike urine or blood tests, which have shorter detection windows, hair tests can reveal drug use over an extended period. For infrequent users, THC (tetrahydrocannabinol), the psychoactive component of cannabis, may still be detectable in hair for several weeks to months after use.

The exact timeframe depends on factors such as the rate of hair growth, the length of the hair sample collected, and the sensitivity of the testing method. While a single instance of use may not typically result in prolonged detection, repeated or regular use can accumulate THC metabolites in the hair, potentially surpassing the cutoff threshold set by the testing facility.

How Much THC to Show Up on a Hair Test?

The amount of THC required to produce a positive result in a hair test is influenced by various factors, including individual differences in metabolism and the sensitivity of the testing method. While a single puff or hit may not typically result in high enough THC levels to trigger a positive result, repeated or regular use can accumulate THC-COOH in hair, surpassing the established cutoff threshold.

The cumulative effect of THC deposition in hair highlights the importance of considering the frequency and regularity of cannabis use when evaluating hair test results. This nuanced understanding allows for a more accurate assessment of an individual’s drug use history and helps determine whether THC levels are indicative of sporadic or chronic use.


In navigating the complexities of THC levels in hair tests, it’s crucial for individuals, incredibly infrequent smokers, to understand the nuances of detection thresholds. While a single exposure is less likely to result in a positive test, cumulative use over time can lead to elevated THC levels in hair. As testing methodologies continue to evolve, staying informed about the latest research and laboratory practices is essential for those concerned about the implications of cannabis use on their hair test results. Ultimately, awareness and education are vital in making informed decisions about drug testing and understanding what is a high THC level in hair